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#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <sstream>
#include <set>
#include <map>
#include <vector>
#include <list>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <string>
#include <queue>
#include <bitset>		//UWAGA - w czasie kompilacji musi byc znany rozmiar wektora - nie mozna go zmienic
#include <cassert>
#include <iomanip>		//do setprecision
#include <ctime>
#include <complex>
using namespace std;

#define FOR(i,b,e) for(int i=(b);i<(e);++i)
#define FORQ(i,b,e) for(int i=(b);i<=(e);++i)
#define FORD(i,b,e) for(int i=(b)-1;i>=(e);--i)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define ALL(u) (u).begin(),(u).end()

#define ST first
#define ND second
#define PB push_back
#define MP make_pair
#define LL long long
#define ULL unsigned LL
#define LD long double

typedef pair<int, int> PII;

const double pi = 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342;

const int MR = 310;

bool done0, done1[MR], done2[MR][MR], done3[MR][MR][MR], ban[MR];

vector<int> g[MR];

PII dp[MR];

vector<int> getChain(int n)
{
	FORD(i, n, 0)
	{
		if (ban[i])
			continue;

		dp[i] = MP(1, -1);
		for (int j : g[i])
			if (!ban[j])
				dp[i] = max(dp[i], MP(1 + dp[j].first, j));
	}

	int best = -1;
	REP(i, n)
		if (!ban[i]
			&& (best == -1 || dp[i].first > dp[best].first))
			best = i;

	vector<int> res;
	while (best != -1)
	{
		res.push_back(best);
		best = dp[best].second;
	}

	return res;
}

int res;

void go(int lvl, int k, int n, vector<int>& banned)
{
	if (!lvl)
	{
		if (done0)
			return;

		done0 = 1;
	}
	else if (lvl == 1)
	{
		if (done1[banned.front()])
			return;

		done1[banned.front()] = 1;
	}
	else if (lvl == 2)
	{
		auto tmp = banned;
		sort(tmp.begin(), tmp.end());
		if (done2[tmp.front()][tmp.back()])
			return;

		done2[tmp.front()][tmp.back()] = 1;
	}
	else if (lvl == 3)
	{
		auto tmp = banned;
		sort(tmp.begin(), tmp.end());
		if (done3[tmp.front()][tmp[1]][tmp.back()])
			return;

		done3[tmp.front()][tmp[1]][tmp.back()] = 1;
	}

	auto chain = getChain(n);

	res = min(res, (int)chain.size());

	if (lvl < k)
		for (int c : chain)
		{
			ban[c] = 1;
			banned.push_back(c);
			go(lvl + 1, k, n, banned);
			banned.pop_back();
			ban[c] = 0;
		}
}

int main()
{
	int n, m, k;
	scanf("%d%d%d", &n, &m, &k);
	REP(i, m)
	{
		int x, y;
		scanf("%d%d", &x, &y); x--; y--;
		g[x].push_back(y);
	}

	res = n;

	vector<int> banned;
	go(0, k, n, banned);

	printf("%d\n", res);

	return 0;
}