func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, t;   char S[25][100005];   long long f[1048576], dp[1048576];   int ans;   inline void Read(int &p) {     p = 0;     char c = getchar();     for (; c <  0  || c >  9 ; c = getchar())       ;     for (; c >=  0  && c <=  9 ; c = getchar()) p = p * 10 + c -  0 ;   }   inline void XorFWT(int n, long long *A) {     for (int i = 1; i < n; i <<= 1) {       for (int j = 0; j < n; j += (i << 1)) {         for (int k = 0; k < i; k++) {           long long x = A[j + k] + A[j + k + i];           long long y = A[j + k] - A[j + k + i];           A[j + k] = x, A[j + k + i] = y;         }       }     }   }   inline void XorIFWT(int n, long long *A) {     for (int i = 1; i < n; i <<= 1) {       for (int j = 0; j < n; j += (i << 1)) {         for (int k = 0; k < i; k++) {           long long x = A[j + k] + A[j + k + i];           long long y = A[j + k] - A[j + k + i];           A[j + k] = x / 2;           A[j + k + i] = y / 2;         }       }     }   }   inline void mul(long long *A, long long *B, int w) {     for (int i = 0; i < w; i++) A[i] = A[i] * B[i];   }   int main() {     scanf( %d%d , &n, &m);     for (int i = 1; i <= n; i++) scanf( %s , S[i] + 1);     for (int i = 1; i <= m; i++) {       int v = 0;       for (int j = 1; j <= n; j++) v = v * 2 + S[j][i] -  0 ;       f[v]++;     }     for (int i = 1; i < (1 << n); i++) dp[i] = dp[i - (i & -i)] + 1;     for (int i = 0; i < (1 << n); i++) dp[i] = min(dp[i], n - dp[i]);     XorFWT(1 << n, f);     XorFWT(1 << n, dp);     mul(f, dp, 1 << n);     XorIFWT(1 << n, f);     ans = n * m;     for (int i = 0; i < (1 << n); i++) ans = min(ans, int(f[i]));     printf( %d n , ans);   }   