#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>
#define rep( i, n, m ) for(ll i = ( n ); i < ( m ); i++)
using ll = long long int;

int give_water( int* array, int begin, int end );

int main( void ){
	int n;
	if (!scanf( "%d", &n ))
		return 0;
	int* array = new int[ n ];
	rep( i, 0, n ){
		if (!scanf( "%d", array + i ))
			return 0;
	}
	int count = 0;
	for(int i = n - 1; i >= 0; i--){
		if (array[ i ] == ( n - count ))
			count++;
	}
	printf( "%d\n", n - count );
	return 0;
}