#include<bits/stdc++.h>
using namespace std;

#define ll						long long
#define D						double
#define pb						push_back
#define mpp						make_pair
#define sf						scanf
#define pf						printf
#define ff						first
#define ss						second
#define sz						100005
#define sq(x)					x*x
#define eps						1e-8
#define PI						(2*acos(0.0))
#define mem(a, b)				memset(a, b, sizeof a)
#define dist(x1, y1, x2, y2)	sqrt(sq(x1-x2)+sq(y1-y2))
#define FastIO					ios_base::sync_with_stdio(0); cin.tie(0)
const int inf = 0x7f7f7f7f;
int dx[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int dy[] = {-1, 0, 1, -1, 1, -1, 0, 1};
int a[11],b[11];

int main()
{
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    FastIO;
    string st;
    int lo=0,up=0,szz,sp=0,dig=0;

    int n;
    cin>>n;
	    cin>>st;
    szz = st.size();
    for(int i=0; i<szz; i++)
    {
		if(st[i]>='a' && st[i]<='z')
		lo++;
		else if(st[i]>='A' && st[i]<='Z')
		up++;
		else if(st[i]>='0' && st[i]<='9')
		dig++;
		else
		sp++;
	}
	//cout<<sp<<endl;
	if(lo>0)
	lo = 1;
	if(up>0)
	up = 1;
	if(dig>0)
	dig = 1;
	if(sp>0)
	sp = 1;
	int cnt = lo+up+dig+sp;
	//cout<<cnt<<" "<<szz<<endl;
	int val = 4-cnt;
	int x = szz-cnt;
	if(cnt==4 && szz>=6)
	cout<<0<<endl;
	else if(cnt==4 && szz<6)
	cout<<6-szz<<endl;
	else if(cnt<4)
	{
		int x = 4-cnt;
		if(x+szz>=6)
		cout<<x<<endl;
		else
		cout<<6-szz<<endl;
	}
	//main();
    return 0;
}