3SUM

# from random import randint

# l = randint(0, 10**9 - 1)
# itemset = set(randint(0,l) for _ in range(1000000))

def threesum(n,x,ai):
    seen = {}
    e = enumerate(ai,1)
    
    for index1, num1 in e:
        for index2, num2 in e:
            if x-(num1+num2) in seen:
                if index1 != seen[x-(num1+num2)] and seen[x-(num1+num2)] != index2 and index1 != index2:
                    return index1,seen[x-(num1+num2)], index2
            else:
                seen[num1] = index1
                seen[num2] = index2
    return "IMPOSSIBLE"


if __name__ == "__main__":
    # print(threesum(None,1000,itemset))
    n,x = map(int, input().split())
    ai = list(map(int, input().split()))
    res = threesum(n,x,ai)
    if type(res) == str:
        print(res)
    else:
        for x in res:
            print(x, end = ' ')


"""
Input:
4 8
2 7 5 1

Output:
1 3 4
"""

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED