#include<bits/stdc++.h>
using namespace std;
bool cr1,cr2,cr3,cr4,cr5;
int main()
{
    int n,ans=0;
    cin>>n;
    string s;
    cin>>s;
    for(int i=0;i<n;i++)
    {
        if(s[i]>='0' && s[i]<='9')
            cr2=true;
        else
        if(s[i]>='a' && s[i]<='z')
            cr3=true;
        else
        if(s[i]>='A' && s[i]<='Z')
            cr4=true;
        else
            cr5=true;
    }
    if(!cr2)
        ans++;
    if(!cr3)
        ans++;
    if(!cr4)
        ans++;
    if(!cr5)
        ans++;
    if(n>=6)
    {
        cr1=true;
        cout<<ans<<endl;
        return 0;
    }
    cout<<max(ans,6-n)<<endl;
    return 0;
}