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/g,"a")
		.replace(/1/g,"b")
		.replace(/2/g,"c")
		.replace(/3/g,"d")
		.replace(/4/g,"e")
		.replace(/5/g,"f")
		.replace(/6/g,"g")
		.replace(/7/g,"h")
		.replace(/8/g,"i")
		.replace(/9/g,"j")
		+(i==(0|n)? "n": "a"));
	}
	process.exit();
});