#include <bits/stdc++.h>   using namespace std;   bool check(string& a, string& b) {     if (a.size() != b.size()) return false;     int ind1 = -1, ind2 = -1;     bool check = false;     bool buck[26] = {0};     int count = 0;     for (int i = 0; i < a.size(); i++) {       if (a[i] != b[i]) {         count++;         if (count > 2) return false;         if (ind1 == -1)           ind1 = i;         else           ind2 = i;       } else {         if (buck[a[i] -  a ])           check = true;         else           buck[a[i] -  a ] = true;       }     }     if (count == 1) return false;     if (count == 0) {       return check;     }     return (a[ind1] == b[ind2]) && (a[ind2] == b[ind1]);   }   int main() {     string a, b;     cin >> a;     cin >> b;     if (check(a, b))       cout <<  YES  << endl;     else       cout <<  NO  << endl;     return 0;   }   