Multiplying by Rotation

http://acm.hust.edu.cn/vjudge/contest/view.action?cid=29821#problem/C

// File Name: bo_jwolf3.cpp
// Author: rudolf
// Created Time: 2013年08月21日 星期三 15:12:37

#include<vector>
#include<list>
#include<map>
#include<set>
#include<deque>
#include<stack>
#include<bitset>
#include<algorithm>
#include<functional>
#include<numeric>
#include<utility>
#include<sstream>
#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<ctime>

using namespace std;

int main()
{
int n , a , b ;
while( scanf( "%d%d%d" , &n , &a, &b ) != EOF )
{
long long s = a * b ;
int ans = 1 ;
while( s != a )
{
ans++ ;
s = s % n * b + s / n ;
}
cout << ans << endl ;
}
return 0;
}