'use strict'

const main = (INPUT) => {
  const W = INPUT.split('\n').slice(1)
  let tmp = W.filter((x, i, self) => self.indexOf(x) === i)
  let ans = 'Yes'
  if (tmp.length != W.length) {
    ans = 'No'
  } else {
    for (let i = 0; i < W.length - 1; i++) {
      if (W[i].slice(-1) != W[i + 1].slice(0, 1)) {
        ans = 'No'
      }
    }
  }
  console.log(ans)
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'))
