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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Linq;

namespace agc030_a
{
    class Program
    {
        static void Main(string[] args)
        {
            var text = Console.ReadLine();
            var list = text.Split(' ').ToList();

            var r = int.Parse(list[0]);
            var n = int.Parse(list[1]);
            
            Console.WriteLine(combi(r, n));
        }

        static int combi(int r, int n)
        {
            if (r == 0 || r == n)
                return (1);
            else if (r == 1)
                return (n);
            return (combi(n - 1, r - 1) + combi(n - 1, r));
        }
    }
}