#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
#include <algorithm>
#include <stack>
#include <map>
#include <functional>
#include <cstring>
#include <queue>
#include <cmath>
#include <deque>
#include <list>
#include <iomanip>
#include <fstream>
#include <string>
#include <iterator>
#include <set>
#include <bitset>
using namespace std;

typedef long long LL;
typedef long double LD;
typedef vector<int> VI;
typedef vector<LL> VLL;
typedef vector<char> VCH;
typedef vector<VI> VVI;
typedef vector<VLL> VVLL;
typedef vector<VCH> VVCH;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef pair<LD, LD> PDD;
typedef vector<PII> VPII;
typedef vector<PLL> VPLL;

#define SZ(a) (LL)(a.size())
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for(LL i = (a); i < (b); ++i)
#define RFOR(i, b, a) for(LL i = (b) - 1; i >= a; --i)
#define REP(i, N) FOR(i, 0, N)
#define MP make_pair
#define X first
#define Y second
#define next fake_next
#define left fake_left
#define right fake_right
#define delete fake_delete
const LD PI = acos(-1.0);
const LL MAXN = 1e6;
const LL mod = 1000000007;
const LL INF = 1e9;

int main()
{
	//ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	//freopen("In.txt", "r", stdin);
	
	int n;
	string s;
	cin >> n >> s;

	bool i1 = 0, i2 = 0, i3 = 0, i4 = 0;
	FOR(i, 0, n)
		if (s[i] >= '0' && s[i] <= '9')
			i1 = 1;
		else
			if (s[i] >= 'a' && s[i] <= 'z')
				i2 = 1;
			else
				if (s[i] >= 'A' && s[i] <= 'Z')
					i3 = 1;
				else
					i4 = 1;

	if (n >= 6)
	{
		cout << 4 -( i1 + i2 + i3 + i4);
		return 0;
	}

	int toAdd = 6 - n;
	toAdd = max(toAdd, 4 - (i1 + i2 + i3 + i4));
	cout << toAdd;





	return 0;
}