#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    int num = 0,lc = 0, uc = 0,sp = 0,ans = 0;
    for(int i=0;i<n;i++)
    {
        if(password[i]>47&&password[i]<58) num++;
        else if(password[i]>96&&password[i]<123) lc++;
        else if (password[i]>64&&password[i]<91) uc++;
        else sp++;
    }
    int nl = n;
        if(num==0) nl++;
        if(lc==0) nl++;
        if(uc==0) nl++;
        if(sp==0) nl++;
    if(nl<6) ans = 6-n;
    else ans = nl - n;
    //cout<<sp<<ans;
    return ans;
}

int main() {
    int n;
    cin >> n;
    string password;
    cin >> password;
    int answer = minimumNumber(n, password);
    cout << answer << endl;
    return 0;
}