#include <stdio.h>
int dp[2][502];
int chk[50001];
int i,j,n,k,f;
int main() {
    scanf("&d", &n);
    scanf("&d", &k);
    dp[0][1]=chk[k]=k;
    for (i=1; i<n; i++) {
        for (j=1; j<=i+1; j++) {
            scanf("&d", &k);
            k=(k+dp[f][j-1]>k+dp[f][j]?k+dp[f][j-1]:k+dp[f][j]);
            dp[!f][j]=chk[k]=k;
        }
        f = !f;
    }
    for (i=n*99; i>=0; i--)
        if (chk[i]) {
            printf("&d", i);
            return 0;
        }
    printf("0");
}

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NQo3CjMgOAo4IDEgMCAKMiA3IDQgNAo0IDUgMiA2IDU=

5
7
3 8
8 1 0 
2 7 4 4
4 5 2 6 5