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

int main() {
    int n,i,count=0,left,ans,remain; 
    char str[200];
    int arr[4];
    scanf("%d",&n);
    scanf("%s",str);
    for(i=0;i<4;i++){
        arr[i]=0;
    }
    for(i=0;i<n;i++){
        if(str[i]>='0' && str[i]<='9'){
            arr[0]=1;
        }
        else if(str[i]>='a' &&str[i]<='z'){
            arr[1]=1;
        }
        else if(str[i]>='A' && str[i]<='Z'){
            arr[2]=1;
        }else{
            arr[3]=1;
        }
        if(arr[0]==1 && arr[1]==1 && arr[2]==1 && arr[3]==1){
            break;
        }
    }
    count=0;
    for(i=0;i<4;i++){
        count+=arr[i];
    }
    left=4-count;
    remain=6-left-n;
    if(remain>0){
        ans=remain+left;
        printf("%d",ans);
    }else{
        ans=left;
        printf("%d",ans);
    }
    return 0;
}