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 bool kangaroo(int x1, int v1, int x2, int v2) {
        //x1 < x2 => Means v1 > v2!
        //x1+z*v1=x2*z*v2 => (v1-v2)*z=x2-x1 => z=(x2-x1)/(v1-v2)
        if(v1 <= v2)
            return false;
        return (x2-x1)%(v1-v2) == 0;
    }

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

        string[] x1V1X2V2 = Console.ReadLine().Split(' ');

        int x1 = Convert.ToInt32(x1V1X2V2[0]);

        int v1 = Convert.ToInt32(x1V1X2V2[1]);

        int x2 = Convert.ToInt32(x1V1X2V2[2]);

        int v2 = Convert.ToInt32(x1V1X2V2[3]);

        var result = kangaroo(x1, v1, x2, v2);

        textWriter.WriteLine(result ? "YES" : "NO");

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