diff --git a/1828B Permutation Swap/1828B.cpp b/1828B Permutation Swap/1828B.cpp
new file mode 100644
index 0000000..45490a5
--- /dev/null
+++ b/1828B Permutation Swap/1828B.cpp	
@@ -0,0 +1,33 @@
+#include<bits/stdc++.h>
+using namespace std;
+using ll = long long;
+
+
+void solve()
+{
+    int n;
+    cin>>n;
+    vector<int>v(n+1);
+    for(int i=1; i<=n; i++)
+    {
+        cin>>v[i];
+    }
+    int ans=0, diff;
+    for(int i=1; i<=n; ++i)
+    {
+        diff=abs(v[i]-i);
+        ans=__gcd(ans,diff);
+    }
+    cout<<ans<<endl;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int TC = 1;
+    cin >> TC;
+    cin.ignore();
+    while (TC--) solve();
+}
\ No newline at end of file