'use strict'

const main = input => {
	const args = input.split('\n').map(arg => arg.split(' '))
	const n = parseInt(args[0][0], 10)
	const w = args.slice(1, n + 1).map(arg => arg[0])
	const t1 = {}
	let t2 = true

	for (let i = 0; i < n; i++) {
		if (w[i] in t1) t1[w[i]]++
		else t1[w[i]] = 1
	}

	for (let i = 1; i < n; i++) {
		if (w[i - 1][w[i - 1].length - 1] !== w[i][0]) t2 = false
	}

	if ( Object.keys(t1).filter(key => t1[key] > 1).length === 0 && t2 ) console.log('Yes')
	else console.log('No')
}

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