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


int main() {
    int n;
    string s;
    cin>>n>>s;
    int a[]={0,0,0,0};
    for(int i=0;i<n;++i){
        if(s[i]>='0' && s[i]<='9')
            a[0]=1;
        else if(islower(s[i]))
            a[1]=1;
        else if(isupper(s[i]))
            a[2]=1;
        else
            a[3]=1;
    }
    int cnt=0;
    for(int i=0;i<4;++i)
        if(!a[i])
            cnt++;
    cout<<max(cnt,6-n);
    return 0;
}