#include <bits/stdc++.h>

const int maxm = 2e4 + 5;
const int maxn = 105;
int a[maxn][maxm],f[maxn][maxm];
int n,m;

int main() {
	freopen("perfecttour.in","r",stdin);
	freopen("perfecttour.out","w",stdout);
	scanf("%d %d",&n,&m);
	-- m;
	for(int i = 1;i <= n;++ i) {
		for(int j = 1;j <= m;++ j) {
			scanf("%d",&a[i][j]);
		}
	}
	
	int ans = 0,maxval = 0;
	for(int j = 1;j <= m;++ j) {
		for(int i = 1;i <= n;++ i) {
			f[i][j] = std::max(0 , maxval + a[i][j]);
			ans = std::max(f[i][j] , ans);
		}
		maxval = 0;
		for(int i = 1;i <= n;++ i) {
			maxval = std::max(maxval , f[i][j]);
		}
	}
	
	printf("%d",ans);
	return 0;
}