#include <bits/stdc++.h>   using namespace std;   void solve() {     long long n, x;     cin >> n >> x;     string second;     cin >> second;     long long ans = 0;     long long sm = 0;     for (long long i = 0; i < n; i++) {       if (second[i] ==  0 )         sm++;       else         sm--;     }     long long c = 0;     for (long long i = 0; i < n; i++) {       if (sm == 0 && c == x) {         cout << -1 << endl;         return;       }       if ((x - c) % sm == 0 && (x - c) / sm >= 0 && sm != 0) ans++;       if (second[i] ==  0 )         c++;       else         c--;     }     cout << ans << endl;   }   int main() {     long long t;     cin >> t;     while (t--) solve();   }   