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*.
# Question: F - 2
# Assignment 7
# Daniel Perez, bd2255

def rainy(SHU,S,E):
    minimum = 0

    current = S
    while True:
        if SHU[current] == S:
            if S == E:
                return minimum
            return -1
        elif SHU[current] == E:
            minimum += 1
            return minimum
        current = SHU[current]
        minimum += 1
            
        

RAW_1 = input().split(' ')
RAW_2 = input().split(' ')

SIZE = int(RAW_1[0])
S = int(RAW_1[1]) - 1
E = int(RAW_1[2]) - 1

for i in range(SIZE):
    RAW_2[i] = int(RAW_2[i]) - 1



print(rainy(RAW_2,S,E))


    	  			  		        	 		  			