C. Table Tennis Game 2

C. Table Tennis Game 2

time limit per test
2 seconds

memory limit per test
512 megabytes

input
standard input

output
standard output

Misha and Vanya have played several table tennis sets. Each set consists of several serves, each serve is won by one of the players, he receives one point and the loser receives nothing. Once one of the players scores exactly k points,
the score is reset and a new set begins.

Across all the sets Misha scored a points in total, and Vanya scored b points.
Given this information, determine the maximum number of sets they could have played, or that the situation is impossible.

Note that the game consisted of several complete sets.

Input

The first line contains three space-separated integers k, a and b (1 ≤ k ≤ 109, 0 ≤ a, b ≤ 109, a + b > 0).

Output

If the situation is impossible, print a single number -1. Otherwise, print the maximum possible number of sets.

Examples

input

11 11 5

output

1

input

11 2 3

output

-1

Note

Note that the rules of the game in this problem differ from the real table tennis game, for example, the rule of "balance" (the winning player has to be at least two points ahead to win a set) has no power within the present problem.

题目链接：http://codeforces.com/contest/765/problem/C

英语不好真是坑死人啊，一开始读错了题，硬推了一个多小时敲了个代码，错了，然后又读题，这次没读错，但是写成了最小，我的天。

题目的意思是说两个人玩游戏，最终两个人的得分为a，b，当两个人的得分为k时开下一场，问最多经过几场比赛，读懂题之后秒A，一遍过。。。我的内心￥……*！@#￥……&*

代码：

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;
int main(){
long long a,b,k;
cin>>k>>a>>b;
if(a<b){
a=a^b;
b=a^b;
a=a^b;
}
if(a<k&&b<k){
cout<<"-1"<<endl;
}
else if(a%k&&b<k){
cout<<"-1"<<endl;
}
else{
long long sum=a/k;
sum+=(b/k);
cout<<sum<<endl;
}
return 0;
}