#!/usr/bin/env pypy3

import array


def minimum_number_of_operations(n, xs):
    idxs = array.array("L", (0 for _ in range(n + 1)))
    for i, x in enumerate(xs, start=1):
        idxs[x] = i
    return idxs.index(1) - 1


def main():
    n = int(input())
    xs = array.array("L", map(int, input().split()))
    print(minimum_number_of_operations(n, xs))


if __name__ == '__main__':
    main()