#include <iostream>
#include <climits>
using namespace std;
int N,M, i, j,a[500][500],b[500][500], maxim=INT_MIN;
int main(){
cin>>N>>M;
for(i=1; i<=N; ++i){
for(j=1; j<=M; ++j)
cin>>a[i][j];
for(i=1; i<=N; ++i)
for(j=1; j<=M; ++j)
{b[i][j]=b[i-1][j]+a[i][j];
if(b[i][j]>maxim) {maxim=b[i][j];}
}
cout<<maxim;
}