const rl=require("readline").createInterface(process.stdin,process.stdout);

rl.once("line",n=>{
	for(var i=1;i<=(0|n);i=0|i+1){
		console.log("a"+(""+i)
		.replace("0","a")
		.replace("1","b")
		.replace("2","c")
		.replace("3","d")
		.replace("4","e")
		.replace("5","f")
		.replace("6","g")
		.replace("7","h")
		.replace("8","i")
		.replace("9","j")
		+(i==(0|n)? "n": "a"));
	}
	process.exit();
});