#include <bits/stdc++.h>
using namespace std;
long long f[101][101];
int main() {
    freopen("TST.INP","r",stdin);
    freopen("TST.OUT","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int n,k; cin >> k >> n;
    for(int i=1;i<=k;i++) {
        for(int j=1;j<=n;j++) {
            long long x; cin >> x;
            if(j>=i) f[i][j]=max(f[i][j-1],f[i-1][j-1]+x);
        }
    }
    cout << f[k][n];
    return 0;
}

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NCA2CjEgMSA2IDQgMyAxMAo5IDEgNCA3IDIgNwo3IDIgNiAxMCAyIDMKNiAxMCA3IDEgMyA5

4 6
1 1 6 4 3 10
9 1 4 7 2 7
7 2 6 10 2 3
6 10 7 1 3 9