#include <bits/stdc++.h>
using namespace std;
int main()
{
    int n,i,j;
    char a[102];
    int count=0,count1=0,count2=0,count3=0,count4=0;
    cin>>n>>a;
    for(i=0;i<n;i++)
    {
        if(a[i]>=65 && a[i]<=90)
            count1=1;
        else if(a[i]>=97 && a[i]<=122)
            count2=1;
        else if(a[i]>=48 && a[i]<=57)
            count3=1;
        else 
            count4=1;
    }
    count+=count1+count2+count3+count4;    
    if(n>=6)
    {
        cout<<4-count<<endl;
    }
    else
    {
        if(n+4-count>=6)
            cout<<4-count<<endl;
        else
            cout<<6-n<<endl;
    }
    return 0;
}