#include<bits/stdc++.h>
using namespace std;
int n;
char s[1000001];
bool angka, kecil, besar, simbol;
int cnt;
int main()
{
	scanf("%d", &n);
	scanf("%s", s);
	for (int i = 0; i < n; i++)
	{
		if ((s[i]-'0'>=0)and(s[i]-'0'<=9)) angka = true;
		if ((s[i]-'a'>=0)and(s[i]-'a'<=25)) kecil = true;
		if ((s[i]-'A'>=0)and(s[i]-'A'<=25)) besar = true;
		if (s[i]=='!') simbol = true;	
		if (s[i]=='@') simbol = true;
		if (s[i]=='#') simbol = true;
		if (s[i]=='$') simbol = true;
		if (s[i]=='%') simbol = true;
		if (s[i]=='^') simbol = true;
		if (s[i]=='&') simbol = true;
		if (s[i]=='*') simbol = true;
		if (s[i]=='(') simbol = true;
		if (s[i]==')') simbol = true;
		if (s[i]=='-') simbol = true;
		if (s[i]=='+') simbol = true;
	}	
	if (angka) cnt++;
	if (kecil) cnt++;
	if (besar) cnt++;
	if (simbol) cnt++;
	printf("%d\n", max(4-cnt, 6-n));
}