hide handkerchief

The Children’s Day has passed for some days .Has you remembered something happened at your childhood? I remembered I often played a game called hide handkerchief with my friends.

Now I introduce the game to you. Suppose there are N people played the game ,who sit on the ground forming a circle ,everyone owns a box behind them .Also there is a beautiful handkerchief hid in a box which is one of the boxes .

Then Haha(a friend of mine) is called to find the handkerchief. But he has a strange habit. Each time he will search the next box which is separated by M-1 boxes from the current box. For example, there are three boxes named A,B,C, and now Haha is at place
of A. now he decide the M if equal to 2, so he will search A first, then he will search the C box, for C is separated by 2-1 = 1 box B from the current box A . Then he will search the box B ,then he will search the box A.

So after three times he establishes that he can find the beautiful handkerchief. Now I will give you N and M, can you tell me that Haha is able to find the handkerchief or not. If he can, you should tell me "YES", else tell me "POOR Haha".

There will be several test cases; each case input contains two integers N and M, which satisfy the relationship: 1<=M<=100000000 and 3<=N<=100000000. When N=-1 and M=-1 means the end of input case, and you should not process the data.

For each input case, you should only the result that Haha can find the handkerchief or not.

3 2
-1 -1

YES

HDU 2007-6 Programming Contest

xhd

题目大意及思路：

给你两个数N,M，求是否在N的范围内不断的循环可以把这些数都遍历一遍，每次移动M步，其实只要两个数互质，经过转N次之后，每个数字都会被访问到。

#include<iostream>
#include<cstdio>

using namespace std;

int main(){
    int n,m;
    while(scanf("%d%d",&n,&m)!=EOF&&(m!=-1||n!=-1)){
        while(n%m!=0){//辗转相除法.
            m=n%m;n=m;
        }
        if(m==1) printf("YES\n");
        else printf("POOR Haha\n");
    }
    return 0;
}