#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdlib>

using namespace std;

int minimumNumber(int n, string password) {
    // Return the minimum number of characters to make the password strong
    bool cond[4] = {0,0,0,0};
    
    for(int i=0;i<n;i++){
    	int mark = (int)password[i];
    	if(mark>96 && mark<123)
    		cond[0] = 1;
    	else if(mark>64 && mark<91)
    		cond[1] = 1;
    	else if(mark>47 && mark<58)
    		cond[2] = 1;
    	else if((mark>32 && mark<39) || (mark>39 && mark<44) || (mark == 45) || (mark == 94) || mark == 64)
    		cond[3] = 1;
	}
	
	int temp = 0;
	for(int i = 0; i < 4;i++)
		if(cond[i] == 0)
			temp++;
	
	int temp2 = 0;
	if(n<6)
		temp2 = 6-n;
	
	if(temp2>temp)
		return temp2;
	else
		return temp;
}

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