#include <bits/stdc++.h>
using namespace std;
map<pair<char,char>,bool>m;
int main(){
	int n;
	cin>>n;
	int sum=0;
	while(n--){
		string x;
		cin>>x;
		if(!m.count(make_pair<char,char>(x[0],x[1]))){
			m[make_pair<char,char>(x[0],x[1])]=1;
			sum++;
		}
	}
	cout<<52-sum;
}