func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m;   int main() {     cin >> n >> m;     if (n == 1) {       cout << 1;       exit(0);     }     cout << fixed << setprecision(12)          << 1.0 / n + (1.0 * (n - 1)) / n * (1.0 * (m - 1)) / (m * n - 1);   }   