rt

#include<bits/stdc++.h>
using namespace std;
struct zjs{
	char c,m;
}q[66];
int cmp(zjs x,zjs y){
	return x.c>y.c;
	
}
int main(){
	int n,ans=0;
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>q[i].c>>q[i].m;
	}
	sort(q+1,q+1+n,cmp);
	for(int i=1;i<=n;i++){
		ans++;
		if(q[i].c==q[i-1].c&&q[i].m==q[i-1].m){
			ans--;
		}
	}
	cout<<52-ans;
}