C

#include <stdio.h>
#include <limits.h>

#define MAXSIZE 505
#define max(a,b) ((a)>(b)?(a):(b))
int n, f[MAXSIZE][MAXSIZE];

void init() {
    scanf("%d", &n);
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j <= i; ++j) {
            scanf("%d", &f[i][j]);
        }
    }
}

int main() {
    init();

    for (int i = 1; i < n; ++i) {
        for (int j = 0; j <= i; ++j) {
            int preSum = INT_MIN;
            if (j > 0) {
                preSum = f[i-1][j-1];
            }
            if (i > j) {
                preSum = max(preSum, f[i-1][j]);
            }
            f[i][j] += preSum;
        }
    }

    int res = INT_MIN;
    for (int j = 0; j < n; ++j) {
        res = max(res, f[n-1][j]);
    }
    printf("%d\n", res);

    return 0;
}