CF478C.Table Decorations

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.

你有 $r$ 个红色气球、$g$ 个绿色气球和 $b$ 个蓝色气球。为了装饰宴会中的一张桌子，恰好需要三个气球。挂在同一张桌子上的三个气球不能是同一种颜色。已知每种颜色气球的数量，最多能装饰多少张桌子 $t$？

你的任务是编写一个程序，对于给定的 $r$、$g$ 和 $b$，求出满足上述要求所能装饰的最大桌子数 $t$。

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.

单行包含三个整数 $r$、$g$ 和 $b$（$0 \le r,\,g,\,b \le 2\cdot10^9$），分别表示红色、绿色和蓝色气球的数量。这些数字之间恰好由一个空格分隔。

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

输出一个整数 $t$ —— 按照要求所能装饰的桌子的最大数量。

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.

在第一个样例中，你可以用以下气球组合来装饰桌子：“rgg”、“gbb”、“brr”、“rrg”，其中“r”、“g”和“b”分别代表红色、绿色和蓝色气球。