//赛时代码
#include<bits/stdc++.h>
using namespace std;
int n;
const int N=53;
char poker[N],poker11[N];
int cnt;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>poker[i]>>poker11[i];
		for(int j=0;j<=i;j++){
			if(poker[i]==poker[j]&&poker11[i]==poker11[j]) cnt++;
			if(cnt>52){
				cout<<51;
				return 0;
			}
		}
	}
	if(n==0){
		cout<<52;
		return 0;
	}
	if(n==1){
		cout<<51;
		return 0;
	}
	cout<<52-n+cnt;
	return 0;
}