'use strict'

const main = (INPUT) => {
  const input = INPUT.split('\n')
  const N = Number(input[0])
  let ans = 'Yes'
  let tmp = input.filter((x, i, self) => self.indexOf(x) === i)
  if (tmp.length != N) {
    ans = 'No'
  } else {
    for (let i = 2; i < input.length; i++) {
      if (input[i - 1].slice(-1) != input[i].slice(0, 1)) {
        ans = 'No'
        break
      }
    }
  }

  console.log(ans)
}

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