#include <bits/stdc++.h>

using namespace std;

#define MAXN 5005
int n, m;
int dp[MAXN][MAXN], mat[MAXN][MAXN];

int main(){
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            cin >> mat[i][j];

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            dp[i][j] = mat[i][j] + max(dp[i-1][j], dp[i][j-1]);

    cout << dp[n][m] << "\n";
}