#include<stdio.h>
int main()
{
    int all = 0 , desk = 0, n, left, i;
    printf("请输入礼物的种类：");
    scanf("%d",&n);
    int a[n];
    scanf("%d",&a[0]);
    left = a[0];
    all += a[0];
    for( i = 1 ; i < n ; i++ )
    {
        scanf("%d",&a[i]);
        all += a[i];
        if( a[i] >= left )
        {
            desk += 2*left;
            left = a[i] - left;
        }
        else
        {
            desk += 2*a[i];
            left -= a[i];
        }
    }
    if( all >= 2*desk )
    {
        printf("最大的桌子数为%d",desk);
    }
    else
    {
        printf("最大的桌子数为%d",all/2);
    }
    return 0;
}