using Hitachi2020.Questions;
using Hitachi2020.Extensions;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace Hitachi2020.Questions
{
    public class QuestionB : AtCoderQuestionBase
    {
        public override IEnumerable<object> Solve(TextReader inputStream)
        {
            var abm = inputStream.ReadIntArray();
            var couponCount = abm[2];

            var refrigeratorPrices = inputStream.ReadIntArray();
            var microwavePrices = inputStream.ReadIntArray();
            var cheapest = refrigeratorPrices.Min() + microwavePrices.Min();

            var coupons = new Coupon[couponCount];
            for (int i = 0; i < couponCount; i++)
            {
                var xyc = inputStream.ReadIntArray();
                coupons[i] = new Coupon(xyc[0] - 1, xyc[1] - 1, xyc[2]);
            }

            foreach (var coupon in coupons)
            {
                var price = refrigeratorPrices[coupon.RefrigeratorNo] + microwavePrices[coupon.MicrowaveNo] - coupon.Discount;
                cheapest = Math.Min(cheapest, price);
            }

            yield return cheapest;
        }

        struct Coupon
        {
            public int RefrigeratorNo { get; }
            public int MicrowaveNo { get; }
            public int Discount { get; }

            public Coupon(int refrigeratorNo, int microwaveNo, int discount)
            {
                RefrigeratorNo = refrigeratorNo;
                MicrowaveNo = microwaveNo;
                Discount = discount;
            }
        }
    }
}

namespace Hitachi2020
{
    class Program
    {
        static void Main(string[] args)
        {
            IAtCoderQuestion question = new QuestionB();    // 問題に合わせて書き換え
            var answers = question.Solve(Console.In);
            foreach (var answer in answers)
            {
                Console.WriteLine(answer);
            }
        }
    }
}

#region Base Classes

namespace Hitachi2020.Questions
{

    public interface IAtCoderQuestion
    {
        IEnumerable<object> Solve(string input);
        IEnumerable<object> Solve(TextReader inputStream);
    }

    public abstract class AtCoderQuestionBase : IAtCoderQuestion
    {
        public IEnumerable<object> Solve(string input)
        {
            var stream = new MemoryStream(Encoding.Unicode.GetBytes(input));
            var reader = new StreamReader(stream, Encoding.Unicode);

            return Solve(reader);
        }

        public abstract IEnumerable<object> Solve(TextReader inputStream);
    }

}

#endregion

#region Extensions

namespace Hitachi2020.Extensions
{
    internal static class TextReaderExtensions
    {
        internal static int ReadInt(this TextReader reader) => int.Parse(ReadString(reader));
        internal static long ReadLong(this TextReader reader) => long.Parse(ReadString(reader));
        internal static double ReadDouble(this TextReader reader) => double.Parse(ReadString(reader));
        internal static string ReadString(this TextReader reader) => reader.ReadLine();

        internal static int[] ReadIntArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(int.Parse).ToArray();
        internal static long[] ReadLongArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(long.Parse).ToArray();
        internal static double[] ReadDoubleArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(double.Parse).ToArray();
        internal static string[] ReadStringArray(this TextReader reader, char separator = ' ') => reader.ReadLine().Split(separator);
    }
}

#endregion

Measured memory_bytes: 37724