function solution(new_id) {
let arr=new_id.toLowerCase().split('')
.filter(e=>e==='-'||e==='_'||e==='.'||(e.charCodeAt(0)>=97&&e.charCodeAt(0)<=122)||isNaN(Number(e))===false);
let arr2=[];
for(let i=0;i<arr.length;i++){
if(arr[i]==='.'&&arr[i+1]==='.'){
continue;
}else{
arr2.push(arr[i])
}
}
if(arr2[0]==='.'){
arr2.shift();
}
if(arr2[arr2.length-1]==='.'){
arr2.pop();
}
if(arr2.length===0){
arr2.push('a')
}
if(arr2.length>15){
arr2=arr2.slice(0,15);
}
if(arr2[arr2.length-1]==='.'){
arr2.pop();
}
if(arr2.length<=2){
while(arr2.length!==3){
arr2.push(arr2[arr2.length-1])
}
}
return arr2.join('');
}