#include<bits/stdc++.h>
#define rep(x,y,z) for(int x=y;x<=z;x++)
#define drep(x,y,z) for(int x=y;x>=z;x--)
#define ull unsigned long long
#define ll long long
using namespace std;
inline int read()
{
	int x=0;bool flag=1;char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-')flag=0;ch=getchar();}
	while(ch>='0'&&ch<='9') {x=(x<<3)+(x<<1)+ch-'0';ch=getchar();}
	if(flag) return x;
	return ~(x-1);
} 
inline void write(int x)
{
	if(x<0) {x=~(x-1);putchar('-');}
	if(x>9) write(x/10);
	putchar(x%10+'0');
}
///////////////////////////////////////
const int M=1e2+5;
const int N=2e4+50;
int n1,n2;
int n[M][N];
int ans;
int main()
{
    freopen("perfecttour.in","r",stdin);
	freopen("perfecttour.out","w",stdout);
	n1=read();
	n2=read()-1;
	rep(i,1,n1)
		rep(o,1,n2) n[i][o]=read();
	int ins1=-99999,ins2=0;
	rep(i,1,n2)
	{
		rep(o,1,n1)
		{
			ins1=max(ins1,n[o][i]);
		}
		ins2+=ins1;
		ans=max(ins2,ans);
		ins2=max(ins2,0);
		ins1=-99999;
	}
	write(ans);
	putchar(10);
    return 0;
}

/*
	rep(i,1,n1)
		rep(o,1,n2) n[i][o]=read();
	rep(i,2,n1) n[i][1]=max(max(0,n[i][1]),n[i][1]+n[i-1][1]);
	rep(i,2,n2)//以列为第一层
	{
		a[1][i]=max(max(0,a[1][i]),a[1][i]+n[1][i-1]);
		rep(o,2,n1)//以行为第二层(a数组)
		{
			a[o][i]=max(max(0,a[o][i]),max(a[o][i]+n[o][i-1],a[o][i]+a[o-1][i]))
		}	
	} 
*/