#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* password) {
    // Return the minimum number of characters to make the password strong
 
    int c=0,cl=0,n=0,sl=0;
    int more=0;
    
    for(i=0;i<n;i++)
    {
        char ch=password[i];
         
            if(ch=='0-9')
                    n++;
        
             if(ch>=97 && ch<=122)
                 sl++;
            if(ch=='!' || ch=='@'  ||ch=='#' ||ch=='$' ||ch=='%' || ch=='^' || ch=='()' || ch=='-' || ch=='+' || ch=='*' || ch=='&')
                      c++;
            
            if(ch>=65 || ch<=90)
                cl++;
                       
         }
    if(n==0)
        more ++;
    if(sl==0)
        more ++;
    if(c==0)
        more ++;
    if(cl==0)
        more ++;
    
    
        
    }
    return(n-more);
    
}

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;
}