Write a program to check whether a given number is an ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. Example 1: ~~~ Input: 6 Output: true Explanation: 6 = 2 × 3 ~~~ Example 2: ~~~ Input: 8 Output: true Explanation: 8 = 2 × 2 × 2 ~~~ Example 3: ~~~ Input: 14 Output: false ~~~ Explanation: 14 is not ugly since it includes another prime factor 7. ~~~ var isUgly = function(num) { if(num<=0) return false; if(num==1) return true; while(num>=2 && num%2==0) num/=2; while(num>=3 && num%3==0) num/=3; while(num>=5 && num%5==0) num/=5; return num==1; }; ~~~