#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>

using namespace std;

int main() {
    vector<string> s = {"0123456789", "abcdefghijklmnopqrstuvwxyz", "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "!@#$%^&*()-+"};
    int n;
    string t;
    cin >> n >> t;
    vector<bool> is(4, false);
    for (int i = 0; i < 4; i++)
    {
        for (int x = 0; x < s[i].size(); x++)
            for (int y = 0; y < n; y++)
                if (t[y] == s[i][x])
                    is[i] = true;                  
    }
    int p = 0;
    for (int i = 0; i < 4; i++)
        if (!is[i])
            p++;
    cout << max(p, 6 - n);
    return 0;
}