Solution.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

class Solution {

    static int getMoneySpent(int[] keyboards, int[] drives, int b) {
        var result = -1;
        foreach(var keyboard in keyboards) { //TODO improve(?)
            if(keyboard >= b)
                continue;
            foreach(var drive in drives) {
                var total = keyboard + drive;
                if(total <= b && total > result)
                    result = total;
            }
        }
        return result;
    }

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

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

        int b = Convert.ToInt32(bnm[0]);

        int n = Convert.ToInt32(bnm[1]);

        int m = Convert.ToInt32(bnm[2]);

        int[] keyboards = Array.ConvertAll(Console.ReadLine().Split(' '), keyboardsTemp => Convert.ToInt32(keyboardsTemp))
        ;

        int[] drives = Array.ConvertAll(Console.ReadLine().Split(' '), drivesTemp => Convert.ToInt32(drivesTemp))
        ;
        /*
         * The maximum amount of money she can spend on a keyboard and USB drive, or -1 if she can't purchase both items
         */

        int moneySpent = getMoneySpent(keyboards, drives, b);

        textWriter.WriteLine(moneySpent);

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