#include <bits/stdc++.h>

using namespace std;

int minimumNumber(int n, string password) {
    // Return the minimum number of characters to make the password strong
    int k1[4];
    int k=0;
    for(int i=0;i<4;i++)
        k1[i]=0;
    for(int i=0;i<n;i++){
        if(islower(password[i]))
        {
            k1[0]++;}
        else if(isupper(password[i]))
            k1[1]++;
        else if(password[i]=='0'||password[i]=='1'||password[i]=='2'||password[i]=='3'||password[i]=='4'||password[i]=='5'||password[i]=='6'||password[i]=='7'||password[i]=='8'||password[i]=='9')
            k1[2]++;
        else if(password[i]=='!'||password[i]=='@'||password[i]=='#'||password[i]=='$'||password[i]=='%'||password[i]=='^'||password[i]=='&'||password[i]=='*'||password[i]=='('||password[i]==')'||password[i]=='+'||password[i]=='-')
            k1[3]++;
    }
    for(int i=0;i<4;i++){
        if(k1[i]==0)
        {
            k++;}
    }
    if(k>6-n)
        return k;
    else
        return (6-n);
}

int main() {
    int n;
    cin >> n;
    string password;
    cin >> password;
    int answer = minimumNumber(n, password);
    cout << answer << endl;
    return 0;
}