#include <iostream>
#include <algorithm>
using namespace std;
#define max(a,b) (a>b?a:b)
#define min(a,b) (a<b?a:b)
int main(){
    string s;
    int n,nr=0,i;
    bool a=0,b=0,c=0,d=0;
    cin>>n>>s; 
    for(i=0; i<n; ++i){
        if(int(s[i])>= 97 && int(s[i])<=122)
            b=1;
        else if(int(s[i])>=48 && int(s[i])<=57)
            a=1;
        else if(int(s[i])>=65 && int(s[i])<=90)
            c=1;
        else
            d=1;
    }
    if(!b)
        ++nr;
    if(!a)
        ++nr;
    if(!c)
        ++nr;
    if(!d)
        ++nr;
    if(n<6){
        if(nr>6-n)
            cout<<nr;
        else
            cout<<6-n;
    }
    else
        cout<<nr;
    return 0;
}