#include <iostream>
#include <sstream>
#include <vector>
#include <algorithm>
#include <climits>

#include "krazki.h"
#include "message.h"

using namespace std;

stringstream out;

typedef long long ll;

struct SmallestDiameter
{
	int number;
	ll diameter;
};

ll holeDiameter[1000000];
ll discDiameter[1000000];
vector<SmallestDiameter> smallestDiameters;

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	if (MyNodeId())
		return 0;

	int pipeHeight, numberOfDiscs;
	pipeHeight = PipeHeight();
	numberOfDiscs = NumberOfDiscs();
	for (int i = 0; i < pipeHeight; ++i)
		holeDiameter[i] = HoleDiameter(i + 1);
	for (int i = 0; i < numberOfDiscs; ++i)
		discDiameter[i] = DiscDiameter(i + 1);

	//Szukanie najmniejszych średnic od góry
	SmallestDiameter smallestDiameter;
	int oldNumber = -1;
	ll smallest = LLONG_MAX;
	for (int i = 0; i < pipeHeight; ++i)
	{
		if (holeDiameter[i] < smallest)
		{
			smallestDiameter.number = i - 1;
			smallestDiameter.diameter = holeDiameter[i];
			oldNumber = i;
			smallest = holeDiameter[i];
			smallestDiameters.push_back(smallestDiameter);
		}
	}

	//Wkładanie kolejnych krążków
	auto it = smallestDiameters.rbegin();
	int minimumPosition = pipeHeight - 1;
	for (int i = 0; i < numberOfDiscs; ++i)
	{
		if (minimumPosition == -1)
		{
			minimumPosition = -2;
			break;
		}
		while (it->diameter < discDiameter[i])
		{
			minimumPosition = it->number;
			++it;
		}

		if (it->number >= minimumPosition)
		{
			++it;
		}

		--minimumPosition;

	}

	cout << minimumPosition + 2 << endl;
	return 0;
}