#include <bits/stdc++.h>
#define endl '\n'
typedef long long LL;
const int I = 1e5 + 2;
const LL mod = 1e9 + 7, inf = 1e18;
using namespace std;

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	string num = "0123456789";
	string lower = "abcdefghijklmnopqrstuvwxyz";
	string upper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	string spec = "!@#$%^&*()-+";
	bool isnum = false;
	bool islow = false;
	bool isup = false;
	bool isspec = false;
	int n; cin >> n;
	string s; cin >> s;
	for(char c: s) {
		bool pres = false;
		for(auto x: num) {
			pres |= (c == x);
		}
		isnum |= pres;
		pres = false;
		for(auto x: lower) {
			pres |= (c == x);
		}
		islow |= pres;
		pres = false;
		for(auto x: upper) {
			pres |= (c == x);
		}
		isup |= pres;
		pres = false;
		for(auto x: spec) {
			pres |= (c == x);
		}
		isspec |= pres;
	}
	int ans = (1 - isnum) + (1 - islow) + (1 - isup) + (1 - isspec);
	cout << max(ans, 6 - n) << endl;
	return 0;
}