let n = +prompt('enter only numbers', '');
number:
for (let i = 2; i < n; i++) {
if (n > 2 || n != undefined || n != null || n != 'string') {
for (let j = 2; j < i; j++) {
if (i %j == 0) continue number;
}
}
else {
console.log('enter number please..')
}
console.log(i)
}