#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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