#include <bits/stdc++.h>
using namespace std;


int main() {
    int n,m,a[1000][1000],sum[1000][1000];
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>a[i][j];
        }
    }
    for(int i=1;i<=n;i++){
       for(int j=1;j<=m;j++){
           if(j-1==0){
               sum[i][j]=sum[i-1][j];
           }
           else if(i-1==0){
               sum[i][j]=sum[i][j-1];
           }
           else{
              sum[i][j]=max(sum[i][j-1],sum[i-1][j]);
           }
           sum[i][j]+=a[i][j];
       }
    }
    cout<<sum[n][m];
    return 0;
}

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NCA1CjAgMiAxIDMgNAozIDIgNCAxIDUgCjMgMiAxIDUgMQoyIDMgNCAyIDI=

4 5
0 2 1 3 4
3 2 4 1 5 
3 2 1 5 1
2 3 4 2 2