#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

int minimumNumber(int n, char* p) {
    // Return the minimum number of characters to make the password strong
    int i,sum=0,k=0,a=0,b=0,c=0,t=0,d=0;
        for(i=0;i<n;++i)
        {
            t=p[i];
            if(t>=65 && t<=90)
                ++a;
            else if(t>=97 && t<=122)
                    ++b;
                    else if(t>=48 && t<=57)
                    ++c;
                    else 
                    ++d;
        }
                    if(a==0)
                    sum+=1;
                    if(b==0)
                    sum+=1;
                    if(c==0)
                    sum+=1;
                    if(d==0)
                    sum+=1;
                    if(n>=6)
                    k=k+sum;
                    if(n<6)
                    {
                   k=k+sum;
                        if((k+n)<6)
                            k=6-(k+n)+k;
                    }
                    return k;
}

int main() {
    int n; 
    scanf("%i", &n);
    char* password = (char *)malloc(512000 * sizeof(char));
    scanf("%s", password);
    int answer = minimumNumber(n, password);
    printf("%d\n", answer);
    return 0;
}