# [Codeforces478A] Initial Bet

## 描述 Description

There are five people playing a game called “Generosity”. Each person gives some non-zero number of coins b as an initial bet. After all players make their bets of b coins, the following operation is repeated for several times: a coin is passed from one player to some other player.

Your task is to write a program that can, given the number of coins each player has at the end of the game, determine the size b of the initial bet or find out that such outcome of the game cannot be obtained for any positive number of coins b in the initial bet.

## 输入格式 InputFormat

The input consists of a single line containing five integers c1, c2, c3, c4 and c5 — the number of coins that the first, second, third, fourth and fifth players respectively have at the end of the game (0 ≤ c1, c2, c3, c4, c5 ≤ 100).

## 输出格式 OutputFormat

Print the only line containing a single positive integer b — the number of coins in the initial bet of each player. If there is no such value of b, then print the only value “-1” (quotes for clarity).

43 83 1 100 23

50

Codeforces 478A

## 代码 Code

``````#include <stdio.h>
#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
using namespace std;
int i,j,t,n,m,l,r,k,z,y,x;
int sum;
int main()
{
sum=0;
for (i=1;i<=5;i++) scanf("%d",&x),sum+=x;;
if (sum%5==0 && sum!=0) printf("%d\n",sum/5);
else printf("%d\n",-1);
return 0;
}``````