#include<stdio.h>
int a[100][100];
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        for(int i=1;i<=n;i++)
            for(int j=1;j<=i;j++)
            scanf("%d",&a[i][j]);

        for(int i=2;i<=n;i++){
                int j=1;
            for(;j<=i;j++){
                if(j == 1) a[i][j] += a[i-1][j];
                else if(j == i) a[i][j] += a[i-1][j-1];
                else if(a[i][j] + a[i-1][j] < a[i][j] + a[i-1][j-1])
                    a[i][j] += a[i-1][j];
                else a[i][j] += a[i-1][j-1];
            }


        }
        int minn=0;
         minn = a[n][1];
        for(int i=1;i<=n;i++)if(a[n][i] < minn  ) minn = a[n][i];
        printf("%d\n",minn);
    }

    return 0;
}

sdut2852 小鑫去爬山9dp入門)