#include <bits/stdc++.h>
using namespace std;
#define  ll long long
#define pb push_back
#define F first
#define S second
#define pp pair<int,int>
#define mod 1000000009
#define fast_io ios::sync_with_stdio(false);cin.tie(NULL)
int main(){
	fast_io;
	if(fopen("input.txt", "r"))
	{
		freopen("input.txt", "r", stdin);
		freopen("output.txt","w",stdout);
	}
	int n;
	cin>>n;
	string s;
	cin>>s;
	bool up,lw,dg,sp;
	up=lw=dg=sp=false;
	for(int i=0;i<n;i++){
		if(s[i] >= 65 && s[i] <= 90){
			up=true;
		}
		else if(s[i] >= 97 && s[i] <= 122){
			lw=true;
		}
		else if(s[i] >= 48 && s[i] <= 57){
			dg=true;
		}else{
			sp = true;
		}
	}
	int val = up+lw+dg+sp;
	if(val == 4 && n >= 6){
		cout<<"0";
		return 0;
	}else if(val == 4){
		cout<<6-n;
		return 0;
	}
	if(val < 4 && n >= 6){
		cout<<4-val;
	}else if(val < 4 && n < 6){
		if(n+4-val >= 6){
			cout<<4-val;
		}else{
			cout<<6-n;
		}
	}
	return 0;
}