#include <bits/stdc++.h>
using namespace std;
int n;
char a[53],b[53];
int main(){
//	freopen("poker.in","r",srdin);
//	freopen("poker.out","w",stdout);
	cin >> n;
	int sum = 52-n;
	for(int i=1;i<=n;i++){
		cin >> a[i] >> b[i];
	}	
	for(int i=1;i<=n;i++){
		for(int j=n;j>=i+1;j--){
			if(a[i]==a[j] and b[i]==b[j]) sum++;
		}
	}cout << sum;
	return 0;
}