Problem:
Score : 200 points

Problem Statement

Takahashi wants to gain muscle, and decides to work out at AtCoder Gym.

The exercise machine at the gym has N buttons, and exactly one of the buttons is lighten up.
These buttons are numbered 1 through N.
When Button i is lighten up and you press it, the light is turned off, and then Button a_i will be lighten up. It is possible that i=a_i.
When Button i is not lighten up, nothing will happen by pressing it.

Initially, Button 1 is lighten up. Takahashi wants to quit pressing buttons when Button 2 is lighten up.

Determine whether this is possible. If the answer is positive, find the minimum number of times he needs to press buttons.

Constraints

2 ≤ N ≤ 10^5

1 ≤ a_i ≤ N

Input

Input is given from Standard Input in the following format:

N
a_1
a_2
:
a_N

Output

Print -1 if it is impossible to lighten up Button 2.
Otherwise, print the minimum number of times we need to press buttons in order to lighten up Button 2.

Sample Input 1

3
3
1
2

Sample Output 1

2

Press Button 1, then Button 3.

Sample Input 2

4
3
4
1
2

Sample Output 2

-1

Pressing Button 1 lightens up Button 3, and vice versa, so Button 2 will never be lighten up.

Sample Input 3

5
3
3
4
2
4

Sample Output 3

3

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
#include<vector>
#include<iostream> //c++
/*
int main(){
	int a=0;
	char A[5];
	for (int i = 0; i < 5; i++) {
		scanf("%c\n", &A[i]);
	}
	
	for(int i = 0; i < 5; i++) {
		if (A[i] =='A' &&A[i + 1]=='C') {
			a = 1;
		
		}
	}
	if (a == 1) {
		printf("Yes");

	}
	else {
		printf("No");
	}
}*/

using namespace std;
int main() {
	int g;
	int  N,Num=0;
	vector<int>a;
	scanf("%d", &N);
	for (int i = 0; i < N;i++) {

		cin >> g;

		a.push_back(g);
	

	}
	int p=1;
	while (true) {

		p = a[p];
			Num++;
			if (p == 2) {
				break;
			}
	}
	printf("%d", Num);
	

}