package main

import (
	"fmt"
)

func main() {
	var N int
	fmt.Scanf("%d", &N)
	data := make([]int, N)
	for i := 0; i < N; i++ {
		fmt.Scanf("%d", &data[i])
	}
	mx := N
	for i := N - 1; i >= 0; i-- {
		if data[i] == mx {
			mx--
		}
	}
	fmt.Println(mx)

}