function Main(input) {
    input = input.split('\n');
    var n = Number(input.shift());
    var w = input;

    if(isShiritori(w)){
        console.log('Yes');
    }else{
        console.log('No')
    }

}

function isShiritori(arr) {
    for(var i=0,len=arr.length;i<len-1;i++) {
        if(arr[i][arr[i].length-1] !== arr[i+1][0]) return false;
    }

    var used = {};
    
    for(var i=0,len=arr.length;i<len;i++) {
        if(i!=0) {
            if(used[arr[i]]) return false;
        }
        used[arr[i]] = true;
    }

    return true;
}

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