#!/usr/bin/env python3
# vim: set ts=4 sw=4 et tw=80:

import sys

def find(A, x):
    i = 0
    while i < len(A):
        if A[i] == x:
            return i
        i = i + 1
    return None

if __name__ == "__main__":
    A = [int(x) for x in sys.argv[1:]]
    print(find(A[1:], A[0]))