#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 t[4]={0,0,0,0},k;
    for(k=0;k<n;k++)
    {
        if(p[k]>='0' && p[k]<='9')
            t[0]++;
        else if(p[k]<='z' && p[k]>='a')
            t[1]++;
        else if(p[k]<='Z' && p[k]>='A')
            t[2]++;
        else
            t[3]++;
    }
    int c=0;
    for(k=0;k<4;k++)
    {
        if(t[k]==0)
            c++;
    }
    if(c==0)
    {
       if(n>=6)
           return 0;
        else
            return (6-n);
    }
    else 
    {
        if(n>=6 || (n+c)>=6)
            return c;
        else 
            return (c+(6-(n+c)));
    }
}

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;
}