#include <bits/stdc++.h>
#include<cstring>

using namespace std;

int minimumNumber(int n, string password) {
    // Return the minimum number of characters to make the password strong
    int f1=-1,f2=-1,f3=-1,f4=-1,f5=-1;
    int c;
    int count=0;
    if(n>=6)
    f1=0;
    for(int i=0;i<n;i++)
    {
    c=(int)password[i];
    if(c>=48 && c<=57)
    f2=0;
    if(c>=97 && c<=122)
    f3=0;
    if(c>=65 && c<=90)
    f4=0;
     if(c>=33 && c<=47)
         f5=0;
    }
    if(f1==0 && f2==0 && f3==0 && f4==0 && f5==0)
    return 0;
    else
    {
    if(f2==-1)
    count+=1;
    if(f3==-1)
    count+=1;
    if(f4==-1)
    count+=1;
    if(f5==-1)
    count+=1;
    if(f1==-1)
    {
    if(6-n>count)
    count=6-n;
    }
    }
    return count;
}

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