#include <bits/stdc++.h>
using namespace std;
const int V = 1<<20;
const int N = 22;
const int M = 100005;
 
int n,a[M];
long long dp[V],cnt[V];
char s[N][M];
int calc(int x) {
	int ans = 0;
	while (x) {
		ans+=(x&1);
		x>>=1;
	}
	return ans;
}
 
void FWT(long long *src,int len) {
	for (int sz = 2;sz <= len; sz<<=1) {
		int step = sz>>1;
		for (int i = 0;i < len;i+=sz) {
			for (int j = i;j < i+step;j++) {
				long long a = src[j],b = src[j+step];
				src[j] = a+b;
				src[j+step] = a-b;
			}
		}
	}
}
 
void IFWT(long long *src,int len) {
	for (int sz = 2;sz <= len;sz <<= 1) {
		int step = sz >> 1;
		for (int i = 0;i<len;i+=sz) {
			for (int j = i;j < i+step;j++) {
				long long a = src[j],b = src[j+step];
				src[j] = (a+b)>>1;
				src[j+step] = (a-b)>>1;
			}
		}
	}
}
int main()
{
	int n,m;
	scanf("%d%d",&n,&m);
	for (int i = 0;i<n;i++)
		scanf("%s",s[i]+1);
	for (int i = 1;i<= m;i++) {
		int tmp = 0;
		for (int j = 0;j < n;j++)
			tmp |= ((s[j][i]-'0')<<j);
		cnt[tmp]++;
	}
	int len = 1<<n;
	for (int i = 0;i<len;i++)
	{
		int tmp = calc(i);
		dp[i] = min(tmp,n-tmp);
	}
	FWT(cnt,len);
	FWT(dp,len);
	for (int j = 0;j < len;j++)
		dp[j] *= cnt[j];
	IFWT(dp,len);
	long long ans = n*m+1;
	for (int j = 0;j < len;j++)
		ans = min(ans,dp[j]);
	printf("%lld\n",ans);
	return 0;
}