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


int main()
{
    int n;
    cin>>n;
    string s;
    cin>>s;
    vector <int> a(4,0);
    for(int i=0;i<n;i++)
    {
        if(s[i]>=48&&s[i]<=57)
            a[0]=1;
        else if(s[i]>=65&&s[i]<=90)
            a[1]=1;
        else if(s[i]>=97&&s[i]<=122)
            a[2]=1;
        else 
            a[3]=1;
    }
    int temp=0;
    for(int i=0;i<4;i++)
    {
        if(a[i]==0)
            temp++;
    }
   // cout<<temp<<endl;
    int d=6-n;
    if(d>=0)
    {  if(d>=temp)
          cout<<d;
    else
        cout<<temp;}
    else
        cout<<temp;
        
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}