#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) {
    bool s[5]={false};/*spc_char=false;
                bool lc_ltr=false;
                bool uc_ltr=false;
                bool num=false;
                bool size=false;*/
    for(int i=0;i<n;i++)
    {
        if(password[i]==33||password[i]==64||password[i]==94||password[i]==45||(password[i]>=35 && password[i]<=38) ||(password[i]>=40 && password[i]<=43 ))
            s[0]=true;
        if(password[i]<=57 && password[i]>=48)
            s[3]=true;
        if(password[i]<=90 && password[i]>=65)
            s[2]=true;
        if(password[i]<=122 && password[i]>=97)
            s[1]=true;      
    }
    int count=0;
    for(int i=0;i<4;i++)
    {
        if(s[i]==true)
            count++;
    }
    if(n>=6)
    {
        return 4-count;
    }
    else
    {
        return (count==4||count==n)?6-n:(6-n>=4-count?6-n:4-count);
    }
    
    // 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;
}