#include <bits/stdc++.h>

using namespace std;



int main() {
    int n;
    cin >> n;
    string s;
    cin >>s;
    int c=0;
    int a=0;
    int b=0;
    int d=0;
    int sum=0;
    int i,answer;
    for(i=0;i<n;i++)
    {
        if((int)s[i]>=65&&(int)s[i]<90)
            a=1;
        if((int)s[i]>=97&&(int)s[i]<=122)
            b=1;
        if((int)s[i]>=48&&(int)s[i]<=57)
            c=1;
        if(s[i]=='!'||s[i]=='@'||s[i]=='#'||s[i]=='$'||s[i]=='%'||s[i]=='^'||s[i]=='&'||s[i]=='*'||s[i]=='('||s[i]==')'||s[i]=='-'||s[i]=='+')
            d=1;
      }
    sum=a+b+c+d;
    if(n>=6)
    {
        if(sum==4)
            answer=0;
        else
            answer=4-sum;
    }
    else
    {
        if(sum==4)
            answer=6-n;
        else
        {
            if(4-sum>=6-n)
                answer=4-sum;
            else
                answer=6-n;
        }
    }
    cout << answer << endl;
    return 0;
}