Problem:
Score : 100 points

Problem Statement

Snuke has N integers: 1,2,\ldots,N.
He will choose K of them and give those to Takahashi.

How many ways are there to choose K consecutive integers?

Constraints

All values in input are integers.

1 \leq K \leq N \leq 50

Input

Input is given from Standard Input in the following format:

N K

Output

Print the answer.

Sample Input 1

3 2

Sample Output 1

2

There are two ways to choose two consecutive integers: (1,2) and (2,3).

Sample Input 2

13 3

Sample Output 2

11

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

r, g, b, n = gets.split.map(&:to_i)
ans = 0
0.step(n, r) do |i|
  0.step(n, g) do |j|
    next if n < i + j
    ans += 1 if (n - (i + j)) % b == 0
  end
end
puts ans