#include <iostream>
using namespace std;
int n;
char a[15][15];
int ans;

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= 2; j++) {
			cin >> a[i][j];
		}
	}
	for (int i = 1; i <= n; i++) {
		for (int j = i + 1; j <= n; j++) {
			if (a[i][1] == a[j][1] && a[i][2] == a[j][2]) {
				ans++;
			}
		}
	}
	cout << 52 - n + ans;
}