func_code_string: #include <bits/stdc++.h>   using namespace std;   const int inf = 0x3f3f3f3f;   const int N = 1e5 + 10;   char a[N], b[N];   int main() {     int t;     scanf( %d , &t);     while (t--) {       int n;       scanf( %d , &n);       scanf( %s%s , a, b);       int t = 0;       int t1 = 0, t2 = 0;       for (int i = 0; i < n; i++) {         if (a[i] != b[i]) {           t++;           if (t == 1)             t1 = i;           else if (t == 2)             t2 = i;         }         if (t == 3) break;       }       if (t != 2)         printf( No n );       else {         if (t == 0 || (a[t1] == a[t2] && b[t1] == b[t2]))           printf( Yes n );         else           printf( No n );       }     }     return 0;   }   