Petya and Vasya are playing a game. Petya's got *n* non-transparent glasses, standing in a row. The glasses' positions are indexed with integers from 1 to *n* from left to right. Note that the positions are indexed but the glasses are not.

First Petya puts a marble under the glass in position *s*. Then he performs some (possibly zero) shuffling operations. One shuffling operation means moving the glass from the first position to position *p*<sub class="lower-index">1</sub>, the glass from the second position to position *p*<sub class="lower-index">2</sub> and so on. That is, a glass goes from position *i* to position *p*<sub class="lower-index">*i*</sub>. Consider all glasses are moving simultaneously during one shuffling operation. When the glasses are shuffled, the marble doesn't travel from one glass to another: it moves together with the glass it was initially been put in.

After all shuffling operations Petya shows Vasya that the ball has moved to position *t*. Vasya's task is to say what minimum number of shuffling operations Petya has performed or determine that Petya has made a mistake and the marble could not have got from position *s* to position *t*.
The first line contains three integers: *n*, *s*, *t* (1 ≤ *n* ≤ 10<sup class="upper-index">5</sup>; 1 ≤ *s*, *t* ≤ *n*) — the number of glasses, the ball's initial and final position. The second line contains *n* space-separated integers: *p*<sub class="lower-index">1</sub>, *p*<sub class="lower-index">2</sub>, ..., *p*<sub class="lower-index">*n*</sub> (1 ≤ *p*<sub class="lower-index">*i*</sub> ≤ *n*) — the shuffling operation parameters. It is guaranteed that all *p*<sub class="lower-index">*i*</sub>'s are distinct.

Note that *s* can equal *t*.
#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <utility>
#include <string>
#include <set>
#include <limits>
#include <map>
#include <stack>
#include <queue>
#include <cstring>
#include <cctype>
 
#define ul unsigned long int
#define ull unsigned long long int
#define ll long long int
#define pb(x) push_back(x)
#define mp(x,y) make_pair(x,y)
 
using namespace std;
 
int main()
{
	ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
	long n, s, t, i, ans, curpos, lastpos;
	cin>>n>>s>>t;
	long a[n];
	for(i=0;i<n;i++)
	{
		cin>>a[i];
		a[i] -= 1;		
	}
	s -= 1;
	curpos = s;
	t -= 1;
	ans = 0;
	lastpos = -1;
	while(true)
	{
		if(curpos==t)//success
		{
			break;
		}
		ans++;
		curpos = a[curpos];		
		if(curpos==lastpos || curpos==s)
		{
			ans = -1;
			break;
		}
		lastpos = curpos;
	}
	cout<<ans<<endl;
	return 0;
}
