#include <cstdio>
#include <cmath>
#include <iostream>
#include <set>
#include <algorithm>
#include <vector>
#include <map>
#include <cassert>
#include <string>
#include <cstring>
#include <queue>

using namespace std;

#define rep(i,a,b) for(int i = a; i < b; i++)
#define S(x) scanf("%d",&x)
#define S2(x,y) scanf("%d%d",&x,&y)
#define P(x) printf("%d\n",x)
#define all(v) v.begin(),v.end()
#define FF first
#define SS second
#define pb push_back
#define mp make_pair

typedef long long int LL;
typedef pair<int, int > pii;
typedef vector<int > vi;

int X[4];

int main() {
  int n;
  S(n);
  string s;
  cin >> s;
  rep(i,0,n) {
    if(s[i] >= '0' && s[i] <= '9') X[0] = 1;
    else if(s[i] >= 'a' && s[i] <= 'z') X[1] = 1;
    else if(s[i] >= 'A' && s[i] <= 'Z') X[2] = 1;
    else X[3] = 1;
  }
  int ans = 4;
  rep(i,0,4) ans -= X[i];
  ans = max(ans, 6 - n);
  P(ans);
  return 0;
}