#include<bits/stdc++.h>
#define rep(i,j,k) for(int i=j;i<=k;i++)
#define repp(i,j,k) for(int i=j;i>=k;i--)
#define ls(x) (x<<1)
#define rs(x) ((x<<1)|1)
#define mp make_pair
#define sec second
#define fir first
#define pii pair<int,int>
#define lowbit(i) i&-i
using namespace std;
typedef long long ll;
const int N=22,M=1e6+5,S=(1<<20)+5,inf=2e9+7,mo=998244353;
void read(int &p){
	int x=0,w=1;
	char ch=0;
	while(!isdigit(ch)){
		if(ch=='-')w=-1;
		ch=getchar();
	}
	while(isdigit(ch)){
		x=(x<<1)+(x<<3)+ch-'0';
		ch=getchar();
	}
	p=x*w;
}
int n,m;
int a[N][M];
ll f[S][N];
signed main(){
    read(n),read(m);
    rep(i,1,n){
        rep(j,1,m)
            read(a[i][j]);
    }
    rep(i,1,m){
        int st=0;
        rep(j,1,n)
            if(a[j][i]==-1)st|=(1<<(j-1));
        rep(j,1,n)
            if(a[j][i]!=-1)f[st][j]+=a[j][i];
    }
    int tot=(1<<n)-1;
    rep(i,1,n){
        rep(j,1,n){
            int nwv=(1<<(j-1));
            for(int k=nwv;k<=tot;k+=nwv<<1){
                rep(l,0,nwv-1)
                    f[k+l][i]+=f[k+l-nwv][i];
            }
        }
    }
    ll ans=0;
    rep(st,0,tot){
        ll res=0;
        rep(i,1,n){
            if((st>>(i-1))&1)continue;
            res+=f[st][i];
        }
        ans=max(ans,res);
    }
    printf("%lld\n",ans);
    return 0;
}