#include<bits/stdc++.h>
 
#define X first
#define Y second
#define eb push_back
#define pb pop_back
#define mp make_pair
#define siz(a) int(a.size())
//for traversing the container (bcoz we cannot access linked list etc with direct index)
//c stands for container and it for iterator
#define tr(c, it) \
		for(typeof(c.begin()) it=c.begin() ; it != c.end() ; it++)
		
#define all(c) c.begin(), c.end()
#define present(container, element) (container.find(element) != container.end()) //whether the element is present in the container
 
#define trace2(x, y)             cout <<#x<<": "<<x<<" | "<<#y<<": "<<y<< endl;
#define trace3(x, y, z)          cout <<#x<<": "<<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<endl;
#define trace4(a, b, c, d)       cout <<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<endl;
#define trace5(a, b, c, d, e)    cout <<#a<<": "<<a<<" | "<<#b<<": "<<b<<" | "<<#c<<": "<<c<<" | "<<#d<<": "<<d<<" | "<<#e<<": "<<e<<endl;
#define scan(x) scanf("%lld", &x)
#define print(x) printf("%lld", x)
#define pN printf("\n");
//#define mod (((ll)1000000000) * ((ll)1000000000))
using namespace std;
 
typedef    long long int ll;
typedef unsigned long long int ull;
typedef vector < int > vi;
typedef vector < vi > vvi;
typedef vector < ll > vll;
typedef vector < vll > vvll;
typedef pair < int , int > ii;
const ll mod=666013;
const ll mod2=1e9+9;
const ll maxn = 1e6+5;
const ll maxn1 = 1e7+1;
const int root=1e5+5;
const long long inf = 1e18 + 18;
double pie4=3.1415926535;
//dont do silly mistake as always-
//1-read question properly(dont miss single line)
//2-check maximum array size	 
//3-int or long long int or ull or sort(a+1,a+n+1)-indexing
//4-do u understand question correctly(shampoo)?
//5-MOST IMP-BE CALM YOU CAN DO:)
//6-think edge case or corner case before submitting.


int main(){
	
	ll n,cnt1=0,cnt2=0,cnt3=0,cnt4=0,ans=0,i ;
	
	string s ;
	
	ios_base::sync_with_stdio(false);cin.tie(NULL); cout.tie(NULL);
	
	cin >> n ;
	
	cin >> s ;
	
	for(i=0;i<n;i++){
		
		//trace2(i,s[i]);
		
		if(s[i]>='a' && s[i]<='z'){
		//cout<<"h"<<endl;	
		cnt1++;
	}
		
		else if(s[i]>='A' && s[i]<='Z')
		cnt2++;
		
		else if(s[i]>='0' && s[i]<='9')
		cnt3++;
		
		else
		cnt4++;
	}
	
	if(cnt1)
	ans++;
	
	if(cnt2)
	ans++;
	
	if(cnt3)
	ans++;
	
	if(cnt4)
	ans++;
	
	//trace2(ans,cnt4);
	
	if(n>=6)
	cout<<(4-ans)<<endl;
	
	else{
		
		cout<<max(6-n,4-ans)<<endl;
	}
}