//Perfection is not attainable,but if we chase perfection we can catch excellence.
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define DHOKHA ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
bool a[4];
int main()
{
   DHOKHA;
   ll n;
   cin>>n;
   string s;
   cin>>s;
   ll i;
   for(i=0;i<=n-1;i++)
   {
   	   if(s[i]>=48 && s[i]<=57)
   	   {
   	   	   a[0]=true;
   	   }
   	   else if(s[i]>=97 && s[i]<=122)
   	   {
   	   	   a[1]=true;
   	   }
   	   else if(s[i]>=65 && s[i]<=90)
   	   {
   	   	   a[2]=true;
   	   }
   	   else
   	   {
   	   	  a[3]=true;
   	   }
   }
   ll c=0;
   for(i=0;i<=3;i++)
   {
   	   if(a[i]==false)
   	   {
   	   	c++;
   	   }
   }
   if(n+c<6)
   {
   	 cout<<6-n;
   }
   else
   {
   	cout<<c;
   }
}