#include <iostream>
using namespace std;
int main()
{
	int B[9], W;
	cin >> B[0] >> B[1] >> B[2] >> B[3] >> B[4] >> B[5] >> B[6] >> B[7] >> B[8];
	for (int i = 0; i < 9; i++)
	{
		if (B[i] != i + 1 && B[8] == 10)
		{
			W = i + 1;
			break;
		}
		else W = 10;
	}
	cout << W << endl;

	return 0;
}