#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {int lo=0,up=0,sp=0,di=0;
    for(int i=0;password[i]!='\0';i++)
    {if(isupper(password[i]))
    up++;
    else if(islower(password[i]))
    lo++;
    else if(isdigit(password[i]))
    di++;
    else
    sp++;
    }
    int c=0;
    if(sp==0)
        c++;
    if(lo==0)
        c++;
    if(up==0)
        c++;
    if(di==0)
        c++;
    if(c==0)
    {if(n<6)
            return 6-n;
        else
            return 0;}
    if(c==1)
    {if(n<5)
    return 6-n;
    else
        return 1;}
    if(c==2)
    {if(n<4)
     return 6-n;
     else
     return 2;
    }
    if(c==3)
    {if(n<3)
    return 6-n;
    else
    return 3;}
    if(c==4)
    {if(n<2)
    return 6-n;
    else
    return 4;}
   return 0; 
    
    // Return the minimum number of characters to make the password strong
}

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