CF886A.ACM ICPC

In a small but very proud high school it was decided to win ACM ICPC. This goal requires to compose as many teams of three as possible, but since there were only 6 students who wished to participate, the decision was to build exactly two teams.

After practice competition, participant number i got a score of a__i. Team score is defined as sum of scores of its participants. High school management is interested if it's possible to build two teams with equal scores. Your task is to answer that question.

在一所以小型但极为自豪的高中，校方决定在 ACM ICPC 竞赛中夺冠。这一目标要求尽可能多地组建三人队伍；但由于仅有 6 名学生希望参赛，最终决定恰好组建两支队伍。

在一次模拟竞赛后，第 $i$ 号参赛者的得分为 $a_i$。一支队伍的得分定义为其三名队员得分之和。校方管理层关心的问题是：能否将这 6 名学生恰好分成两支队伍，使得两支队伍的得分相等？你的任务就是回答这个问题。

The single line contains six integers _a_1, ..., _a_6 (0 ≤ a__i ≤ 1000) — scores of the participants

单行包含六个整数 $a_1,\ \dots,\ a_6$（$0\le a_i\le 1000$）——参赛者的得分

Print "YES" (quotes for clarity), if it is possible to build teams with equal score, and "NO" otherwise.

You can print each character either upper- or lowercase ("YeS" and "yes" are valid when the answer is "YES").

如果可以组建得分相等的队伍，则输出 "YES"（引号仅用于明确显示），否则输出 "NO"。

当答案为 "YES" 时，每个字符可使用大写或小写形式（例如 "YeS" 和 "yes" 均为有效输出）。

In the first sample, first team can be composed of 1st, 2nd and 6th participant, second — of 3rd, 4th and 5th: team scores are 1 + 3 + 1 = 2 + 1 + 2 = 5.

In the second sample, score of participant number 6 is too high: his team score will be definitely greater.

在第一个样例中，第一支队伍可以由第 1、2、6 号参赛者组成，第二支队伍由第 3、4、5 号参赛者组成：两支队伍的得分均为 $1 + 3 + 1 = 2 + 1 + 2 = 5$。

在第二个样例中，第 6 号参赛者的得分过高：其所在队伍的总分必定更大。