func_code_string: #include <bits/stdc++.h>   using ll = long long;   using namespace std;   using pii = pair<ll, ll>;   ll mod = 998244353;   int get_p2(int n) {     int i = 0;     while ((1 << i) <= n) i++;     return i - 1;   }   int main() {     ios_base::sync_with_stdio(0);     int t;     cin >> t;     while (t--) {       int n;       cin >> n;       string a, b;       cin >> a >> b;       int need0 = 0, need1 = 0, nneed0 = 0, nneed1 = 0;       for (int i = 0; i < n; i++) {         if (a[i] != b[i]) {           if (a[i] ==  0 )             need0++;           else             need1++;         } else {           if (a[i] ==  0 )             nneed0++;           else             nneed1++;         }       }       int ans = -1;       if (nneed1 - nneed0 == 1) ans = nneed1 + nneed0;       if (need0 == need1)         ans = (ans < 0 ? need0 + need1 : min(ans, need0 + need1));       cout << ans <<   n ;     }     cout.flush();   }   