Problem:
Score : 100 points

Problem Statement

Given is a lowercase English letter C that is not z. Print the letter that follows C in alphabetical order.

Constraints

C is a lowercase English letter that is not z.

Input

Input is given from Standard Input in the following format:

C

Output

Print the letter that follows C in alphabetical order.

Sample Input 1

a

Sample Output 1

b

a is followed by b.

Sample Input 2

y

Sample Output 2

z

y is followed by z.

Solution in Ruby (2.3.3) (judge verdict: Runtime Error)

a = gets.split(' ').map(&:to_i)
b = gets.split(' ').map(&:to_i)
c = b.inject{|a,i| a+=i}
d = 0

b[1].times do |i|
	if c.fdiv(b.length) + i < b[2]
		d = i
		break;
	end
end

puts d == 0 ? -1 : d