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

int main(void) {
  int n;cin >> n;
  vector<string> s(n);
  for (auto&& vec:s) {
    cin >> vec;
  }
  int c=0;
  for(int i=0;i<n-1;i++) {
    for(int j=i+1;j<n;j++) {
      if(s[i] == s[j]) {
        c = 1;
      }
    }
    if (s[i].back() != s[i+1].front()) {
      c = 1;
    }
  }
  if (c ==1) {
    cout << "No" << endl;
  } else {
    cout << "Yes" << endl;
  }
  return 0;
}