#include <cstdlib>
#include <cctype>
#include <cstring>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <fstream>
#include <numeric>
#include <iomanip>
#include <bitset>
#include <list>
#include <stdexcept>
#include <functional>
#include <utility>
#include <ctime>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define MEM(a,b) memset((a),(b),sizeof(a))
const LL INF = 1e9 + 7;
const int N = 5e5 + 10;
int main()
{
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	string s1 = "0123456789";
	string 	s2 = "abcdefghijklmnopqrstuvwxyz";
	string 	s3 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	string 	s4 = "!@#$%^&*()-+";
	map<char, int> mc;
	for (auto &c : s1) mc[c] = 1;
	for (auto &c : s2) mc[c] = 2;
	for (auto &c : s3) mc[c] = 3;
	for (auto &c : s4) mc[c] = 4;
	string str;
	int n;
	cin >> n >> str;
	map<int, int> m;
	for (auto &x : str)
	{
		m[mc[x]] = 1;
	}
	cout << max(6 - n, int(4 - m.size()));
	return 0;
}