#include <cmath>
#include <cstring>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int i,n,ans = 4;
    bool ch[4] = {0};
    string s;
    cin >> n >> s;
    for (i = 0; i < n; i++)
        if (s[i] >= '0' && s[i] <= '9') ch[0] = 1;
        else if (s[i] >= 'a' && s[i] <= 'z') ch[1] = 1;
        else if (s[i] >= 'A' && s[i] <= 'Z') ch[2] = 1;
        else ch[3] = 1;
    for (i = 0; i < 4; i++)
        ans -= ch[i];
    ans = max(6-n,ans);
    cout << ans;
    return 0;
}