function Main(input){
    input = input.split("\n")
    var N = parseInt(input[0],10)
    input.shift()
    var W = input

    for(var i = 0;i < N;i++){
        for(var j = i + 1;j < N;j++){
            if(W[i] === W[j]){
                console.log("No")
                return
            }
        }
    }

    for(var i = 0;i < N - 1;i++){
        if(W[i].slice(-1) !== W[i+1].slice(0,1)){
            console.log("No")
            return
        }
    }

    console.log("Yes")
}

Main(require("fs").readFileSync("/dev/stdin","utf8"))