#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, U b) {
  if (a < b) a = b;
}
template <typename T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <typename T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <typename T>
inline void println(T first) {
  print(first), putchar('\n');
}
template <typename T>
inline void printsp(T first) {
  print(first), putchar(' ');
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a % m)
    if (b & 1) ans = 1LL * ans * a % m;
  return ans;
}
char s[55], t[55];
int vst[26], can[26], flag[26];
int main() {
  int n, m, runs;
  cin >> n >> s;
  for (int i = 0; i < n; i++) {
    if (islower(s[i])) vst[s[i] - 'a'] = 1;
  }
  cin >> m;
  for (int i = 0; i < m; i++) {
    cin >> t;
    int ok = 1;
    for (int j = 0; ok && j < n; j++) {
      if (s[j] == '*' && vst[t[j] - 'a']) ok = 0;
      if (islower(s[j]) && s[j] != t[j]) ok = 0;
    }
    if (ok) {
      runs++;
      for (int j = 0; j < n; j++) {
        if (s[j] == '*') {
          if (flag[t[j] - 'a'] != runs) {
            can[t[j] - 'a']++;
            flag[t[j] - 'a'] = runs;
          }
        }
      }
    } else
      for (int j = 0; j < 26; j++) can[j] += (vst[j] == 0);
  }
  int ans = 0;
  for (int i = 0; i < 26; i++) ans += (can[i] == m);
  println(ans);
  return 0;
}
