15 lines
232 B
C++
15 lines
232 B
C++
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#include<bits/stdc++.h>
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using namespace std;
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int main()
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{
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int k,n,w;
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cin>>k>>n>>w;
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int i,money=0;
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for(i=1;i<=w;i++)
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{
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money=money+i*k;
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}
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if(money>n) cout<<money-n<<endl;
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else cout<<0<<endl;
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}
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