'use strict'

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

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