#include<bits/stdc++.h>
#define cir(i,a,b) for(int i=a;i<b;++i)
using namespace std;
using lint=long long;
class basic_poly{
private:
    template<const int type>
    auto fwtand(vector<lint>&a){
        const auto n=(int)(a.size());
        for(auto h=2;h<n+1;h<<=1){
            const auto midh=h/2;
            for(auto i=0;i<n;i+=h){
                cir(k,i,i+midh) a[k]+=type*a[k+midh];
            }
        }
    }
public:
    auto fwtand(vector<lint>&a,const int n){
        fwtand<1>(a);
    }
    auto ifwtand(vector<lint>&a,const int n){
        fwtand<-1>(a);
    }
} poly;
int main(){
    ios::sync_with_stdio(false),cin.tie(0);
    int n,m;cin>>n>>m;
    vector<vector<lint>> cost(n,vector<lint>(m));
    for(auto&i:cost) for(auto&j:i) cin>>j;
    vector<vector<lint>> state(n,vector<lint>(1<<n));
    cir(i,0,m){
        auto st=0;
        cir(x,0,n) if(cost[x][i]>-1) st|=(1<<x);
        cir(x,0,n) if(st&(1<<x)) state[x][st]+=cost[x][i];
    }
    vector<lint> ans(1<<n);
    cir(i,0,n){
        poly.fwtand(state[i],n);
        cir(s,0,(1<<n)) if(s&(1<<i)) ans[s]+=state[i][s];
    }
    cout<<*max_element(ans.begin(),ans.end())<<'\n';
    return 0;
}