#include<iostream>
#include<cmath>
#include<iomanip>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<vector>
#include<utility>

#define ll long long
#define nl '\n'
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define rall(s)  s.rbegin(), s.rend()
#define ceill(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
using namespace std;

void Fast_IO(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
//     #ifndef ONLINE_JUDGE
//         freopen(“intersection.in”,”r”,stdin), freopen("output.txt", "w", stdout);
//     #endif
}





void solve(){
  ll n; cin>>n;
  ll freq_chars[26]{};
  ll freq_num[10]{};
  ll m =n;
      ll counter =0;
  while(n--){
      string s; cin>>s;
      for(int i=0; i<sz(s); i++){
          if(s[i]>='0' and s[i] <= '9'){
              freq_num[s[i]-'0']++;
              if(freq_num[s[i]-'0']>=m and n==0) counter++;
          }else if(s[i]>='a' and s[i]<='z'){
              freq_chars[s[i]-'a']++;
              if(freq_chars[s[i]-'a']>=m and n==0) counter++;
          }
      }

  }

  if(counter>0){
      cout<<counter<<nl;
      for(int i=0; i<10; i++){
          if(freq_num[i]>=m) cout<<i<<' ';
      }
      for(int i=0; i<26; i++){
          if(freq_chars[i]>=m) cout<<(char)(i+'a')<<' ';
      }
  }else cout<<"No intersect chars";




}

int main(){
    freopen(“intersection.in”, ”r” ,stdin);
    Fast_IO();
int t =1;
//cin>>t;
while(t--){
solve();
}
return 0;
}