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


int main() {
    int n;
    int i,j,k,x,a1=0,a2=0,a3=0,a4=0;
    cin>>n;
    string a;
    cin>>a;
    for(i=0;i<a.length();i++)
    {
        if(a[i]>='a'&&a[i]<='z')
            a1=1;
        else if(a[i]>='A'&&a[i]<='Z')
            a2=1;
        else if(a[i]>='0'&&a[i]<='9')
            a3=1;
        else
            a4=1;
    }
    x=a1+a2+a3+a4;
    if(a.length()+(4-x)<6)
        cout<<6-a.length();
    else
        cout<<4-x;
    return 0;
}