uses math;
var n,i,cnt:longint; password:string[100];
    constraint:array[1..4]of boolean;
begin
    readln(n); read(password);
    fillchar(constraint,sizeof(constraint),false);
    for i:=1 to n do
        if password[i] in ['0'..'9'] then constraint[1]:=true
        else if password[i] in ['a'..'z'] then constraint[2]:=true
        else if password[i] in ['A'..'Z'] then constraint[3]:=true
        else constraint[4]:=true;
    cnt:=0;
    for i:=1 to 4 do inc(cnt,ord(not constraint[i]));
    write(max(cnt,6-n))
end.