You have r red, g green and b blue
balloons. To decorate a single table for the banquet you need exactly three balloons. Three balloons attached to some table shouldn't have the same color. What maximum number t of
tables can be decorated if we know number of balloons of each color?

Your task is to write a program that for given values r, g and b will
find the maximum number t of tables, that can be decorated in the required manner.

The single line contains three integers r, g and b (0 ≤ r, g, b ≤ 2·109)
— the number of red, green and blue baloons respectively. The numbers are separated by exactly one space.

Print a single integer t — the maximum number of tables that can be decorated in the required manner.

In the first sample you can decorate the tables with the following balloon sets: "rgg", "gbb",
"brr", "rrg", where "r",
"g" and "b" represent the red, green and blue balls, respectively.

首先要明确，当最大的气球数量的一半小于另外两种颜色的数量之和，肯定能够组成所有颜色数量之和/3,当最大的

气球数量的一半大于等于另外两种颜色的数量之和，所有组成为2+1，2为最多数量的颜色。

代码：

#include <iostream>

#include <cstdio>

#include <cstdio>

#include <algorithm>

using namespace std;

int main()

{

    long long a[3];

    scanf("%I64d%I64d%I64d",&a[0],&a[1],&a[2]);

    sort(a,a+3);

    long long ans=0;

    if((a[0]+a[1])<=a[2]/2)

    {

       ans=a[0]+a[1];

    }

    else

    {

        ans=(a[0]+a[1]+a[2])/3;

    }

    printf("%I64d\n",ans);

    return 0;

}