Solution.cs

using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Collections;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.Serialization;
using System.Text.RegularExpressions;
using System.Text;
using System;

class Solution {
    static int birthday(List<int> s, int d, int m) {
        var result = 0;
        if(m > s.Count) //special case: not enough chocolate bars
            return result;
        var sum = 0;
        for(var i = 0; i<m; i++)
            sum += s[i];
        var endPos = m;
        while (true)
        {
            if (sum == d)
                result++;
            if (endPos >= s.Count)
                break;
            sum += s[endPos];
            sum -= s[endPos - m];
            endPos++;
        };
        return result;
    }

    static void Main(string[] args) {
        TextWriter textWriter = new StreamWriter(@System.Environment.GetEnvironmentVariable("OUTPUT_PATH"), true);

        int n = Convert.ToInt32(Console.ReadLine().Trim());

        List<int> s = Console.ReadLine().TrimEnd().Split(' ').ToList().Select(sTemp => Convert.ToInt32(sTemp)).ToList();

        string[] dm = Console.ReadLine().TrimEnd().Split(' ');

        int d = Convert.ToInt32(dm[0]);

        int m = Convert.ToInt32(dm[1]);

        int result = birthday(s, d, m);

        textWriter.WriteLine(result);

        textWriter.Flush();
        textWriter.Close();
    }
}