/in/foo.c:6:19: error: variably modified 'f' at file scope
    6 | double mu, sigma, f[N], sum[N];
      |                   ^
/in/foo.c:6:25: error: variably modified 'sum' at file scope
    6 | double mu, sigma, f[N], sum[N];
      |                         ^~~
/in/foo.c: In function 'main':
/in/foo.c:16:53: warning: implicit declaration of function 'min'; did you mean 'main'? [-Wimplicit-function-declaration]
   16 |                                 for(int j = 1; j <= min(X - 1, i); j ++) f[i] += (Y * j - (i - j)) * f[i - j];
      |                                                     ^~~
      |                                                     main