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

int minimumNumber(int len, char* password) {
    int digit=0,lc=0,uc=0,sc=0;
    for(int i=0;i<len;i++){
            int k=password[i];
            if(k>=48 &&k<=57)
                digit++;
            if((k>=33 && k<=47) || (k>=58 && k<=64) )
                sc++;
            if((k>=97 && k<=122))
                lc++;
            if(k>=65 && k<=90)
                uc++;
    }
    //printf("%d   %d  %d   %d   ",digit,lc,uc,sc);
    if(len<6){
        int k=0;
        if(digit==0)
            k++;
        if(lc==0)
            k++;
        if(uc==0)
            k++;
        if(sc==0)
            k++;
        if(len+k<6)
            return 6-len;
        else
            return k;
    }
    int k=0;
    if(digit==0)
        k++;
        if(lc==0)
            k++;
        if(uc==0)
            k++;
        if(sc==0)
            k++;
       return k;
    // Return the minimum number of characters to make the password strong
}

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;
}