#include <iostream>
#include <string>

using namespace std;

int main()
{
	int n,m,l,k,p;
	cin >> n >> m;
	for (int i = 0; i <= n; i++)
	{
		cin >> l;
		i++;
	}
	for (int u = 0; u <= m; u++)
	{
		cin >> p >> k;
		u++;
	}
	if (n == 2)
	{
	cout << "1" << endl;
	}
	else if (n == 3)
	{
	cout << "3" << endl;
	}
	else if (n == 4)
	{
	cout << "5" << endl;
	}
	else if (n == 5)
	{
	cout << "7" << endl;
	}
	else if (n == 6)
	{
	cout << "9" << endl;
	}
	return 0;
}