func_code_string: #include <bits/stdc++.h>   using namespace std;   void solve() {     int n, m;     cin >> n >> m;     if (n == 1)       cout << 0;     else if (n == 2)       cout << m;     else       cout << 2 * m;     puts(  );   }   int main() {     int q;     for (cin >> q; q--;) solve();     return 0;   }   