Problem:
Score : 200 points

Problem Statement

Snuke has come to a store that sells boxes containing balls. The store sells the following three kinds of boxes:

Red boxes, each containing R red balls

Green boxes, each containing G green balls

Blue boxes, each containing B blue balls

Snuke wants to get a total of exactly N balls by buying r red boxes, g green boxes and b blue boxes.
How many triples of non-negative integers (r,g,b) achieve this?

Constraints

All values in input are integers.

1 \leq R,G,B,N \leq 3000

Input

Input is given from Standard Input in the following format:

R G B N

Output

Print the answer.

Sample Input 1

1 2 3 4

Sample Output 1

4

Four triples achieve the objective, as follows:

(4,0,0)

(2,1,0)

(1,0,1)

(0,2,0)

Sample Input 2

13 1 4 3000

Sample Output 2

87058

Solution in C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;

namespace diverta2019_C
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = int.Parse(Console.ReadLine());
            var count = 0;
            var countA = 0;
            var countB = 0;

            for (var i = 0; i < N; i++)
            {
                var str = Console.ReadLine();
                var str2 = str.ToCharArray();

                for (var j=0;j<str.Length-1;j++)
                    if (str[j] == 'A' && str[j+1] == 'B')
                        count++;

                var strB = str.Substring(0, 1);
                if (strB == "B")
                    countB++;
                var strA = str.Substring(str.Length - 1);
                if (strA == "A")
                    countA++;
            }

            var min = Math.Min(countA, countB);
            Console.WriteLine(count + min);
        }
    }
}