#include <bits/stdc++.h>
using namespace std;

int main()
{
int i;
int N;
int iCnt;

	ios::sync_with_stdio( false );
	cin.tie( 0 );

	cin >> N;

vector<int> p( N );
vector<int> A( N );

	iota( A.begin(), A.end(), 1 );
	for( i = 0; i < N; i++ ) cin >> p[ i ];

	iCnt = 0;
	do
	{
		iCnt++;
		if( A == p ) break;
    }
	while( next_permutation( A.begin(), A.end() ) );

	cout << iCnt << endl;

	return 0;
}