JS 100第61題文字列の圧縮

	var n = prompt().split('');
	var sen = "";
	var start = n[0];
	var cnt = 0;
	
	for(var i in n){
		if(n[i] == start){
			cnt++; 
		}else{
			sen+=start+cnt;
			
			start = n[i];
			cnt = 1;
		}
	}
	sen+=start;
	sen+=cnt;
	
	console.log(sen);