83 lines
2.5 KiB
C++
83 lines
2.5 KiB
C++
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#include<bits/stdc++.h>
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using namespace std;
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// Short forms
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#define ll long long
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#define ull unsigned long long
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#define nl '\n'
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#define ff first
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#define ss second
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#define all(x) x.begin(), x.end()
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#define sz(x) (int)(x).size()
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#define pb push_back
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#define mp make_pair
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// Loops
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#define nlp(i, n) for (int i = 0; i < (int)(n); ++i)
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#define lp(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
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#define rlp(i, a, b) for (int i = (int)(a); i > (int)(b); --i)
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#define llp(i,a,b) for (ll i= (ll)(a); i < (ll)(ll)(b); ++i)
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// STLs
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#define pii pair<int, int>
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#define vi vector<int>
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#define vll vector<ll>
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#define vvi vector<vector<int>>
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#define vvl vector<vector<ll>>
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// Outputs
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#define yes cout<<"YES"<<nl
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#define no cout<<"NO"<<nl
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#define dbg(x) cerr << #x <<" "<< x << endl;
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// Constants
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#define PI 3.141592653589793238
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#define INF LONG_LONG_MAX
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#define MOD 1e9+7
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// Faster Input Output
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#define FAST_IO (ios_base:: sync_with_stdio(false),cin.tie(NULL));
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// Maths
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ll fact(ll n) { if(n==0) return 1; ll res = 1; for (ll i = 2; i <= n; i++) res = res * i; return res; }
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ll nPr(ll n, ll r) { return fact(n) / fact(n - r); }
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ll nCr(ll n, ll r) { return fact(n) / (fact(r) * fact(n - r)); }
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ll gcd(ll a, ll b) { if (b == 0) return a; return gcd(b, a % b); }
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ll lcm(ll a, ll b) { return (a * b) / gcd(a, b);}
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ll mypow(ll a, ll b) { ll ans = 1; while(b){ if (b&1) ans = (ans*a) ; b /= 2; a = (a*a); } return ans; }
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bool isPrime(ll n) { if(n <= 1) return false; for(ll i = 2; i <= sqrt(n); i++) if(n % i == 0) return false; return true; }
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/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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void solve()
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{
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int n;
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cin>>n;
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vector<int>str;
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vector<int>end;
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for(int i=0; i<n; ++i)
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{
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int x,y;
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cin>>x>>y;
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str.pb(x);
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end.pb(y);
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}
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for(int i=1; i<n; ++i)
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{
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if(str[i]>=str[0] && end[i]>=end[0])
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{
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cout<<-1<<nl;
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return;
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}
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}
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cout<<str[0]<<nl;
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}
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int main()
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{
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FAST_IO;
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int TC = 1;
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cin >> TC;
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while (TC--) solve();
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}
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