1. Write a function to format time which accepts time in seconds and return a string with formatted time

e.g.

format_time(1)
	//=> "1 second"
format_time(125)
  //=> "2 minutes, 5 seconds"
format_time(2100)
	//=> "35 minutes"
format_time(2115)
	//=> "35 minutes, 15 seconds"



2. Write a function which will format price, input is a float number and returns a string with formatted price
Example:
format_price(1500.129)
 // =>   'Rs 1,500.12'
format_price(-5)
 // =>   'Rs -5.00'
format_price(1000000.5)
 // =>   'Rs 1,000,000.50'



3. Write a function to check if a string is a palindrome and returns 'Nes' or 'No'

e.g.
is_palindrome("asdsa")
 //=> "Yes"
is_palindrome("asddsa")
 //=> "Yes"
is_palindrome("aaadaa")
 //=> "No"


4. Write a function to find the first non repeating letter(ignoring the case) in a given string
e.g.
first_non_repeating_letter("a")
 //=> "a"
first_non_repeating_letter("stress")
 //=> "t"
first_non_repeating_letter("moonmen")
 //=> "e"
first_non_repeating_letter("stress stress")
 //=> " "
first_non_repeating_letter("sTreSS")
 //=> "T"


5. Write a function to find perfect numbers between 1 to n, for given n

perfect_numbers(10)
 //=> [6]
perfect_numbers(29)
 //=> [6,28]
perfect_numbers(400)
 //=> [6,28]