func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long t;     cin >> t;     while (t--) {       long long x, y, p, q;       cin >> x >> y >> p >> q;       if (p == q && x == y) {         printf( 0 n );         continue;       }       if (p == 0 && x == 0) {         printf( 0 n );         continue;       }       if (p == q || p == 0 || q == 0) {         printf( -1 n );         continue;       }       long long i = max(           (x - p * ((y + q - 1) / q) + p - 1) / p,           (p * ((y + q - 1) / q) - (x + ((y + q - 1) / q) * q - y) + q - p - 1) /               (q - p));       printf( %lld n , i * q + ((y + q - 1) / q) * q - y);     }     return 0;   }   