#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password)
{
    int f1=0,f2=0,f3=0,f4=0,f=0;
    for(int i=0;i<n;i++)
    {
        int j=password[i];
        if(j>=65 && j<=90)
        {
           f1=1;
          //  cout<<"f1"<<"1"<<endl;
        }
        if(j>=97 && j<=122)
        {
            f2=1;
            //cout<<"f2"<<endl;
        }
        if(j>=48 && j<=57)
        {
            f3=1;
          //  cout<<"f3";
        }
        if(password[i]=='!'||password[i]=='@'||password[i]=='#'||password[i]=='$'||password[i]=='%'||password[i]=='^'||password[i]=='&'||password[i]=='*'||password[i]=='('||password[i]==')'||password[i]=='-'||password[i]=='+')
        {
            f4=1;
        }
    }
    if(f1==1 && f2==1 && f3==1 && f4==1 && n>=6)
    {
       // cout<<"hello";
        return 0;
    }
    
    f=f1+f2+f3+f4;
    f=4-f;
   // cout<<f<<endl;
    if(f==4 && n<6)
    {
        return 6;
    }
 //  cout<<f<<endl;
    if(n+f<6)
    {
        
        //cout<<"hello1";
        return (6-n);
    }
   // cout<<"hello2";
    return f;
}

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