#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;

char str[105];
bool flag[4];

int main()
{
	int n;
	//char x[100]="!@#$%^&*-+";
	
	scanf("%d",&n);
	scanf("%s",str+1);
	for(int i=1;i<=n;i++){
		if(str[i]<='z'&&str[i]>='a')flag[0]=1;
		else if(str[i]<='Z'&&str[i]>='A')flag[1]=1;
		else if(str[i]<='9'&&str[i]>='0')flag[2]=1;
		else flag[3]=1;
	}
	printf("%d\n",max(6-n,(!flag[0])+(!flag[1])+(!flag[2])+(!flag[3])));
	return 0;
}