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#include <bits/stdc++.h>
using namespace std;

const int MAXN = 505;

vector<int> v[MAXN];
int vis[MAXN];
int del[MAXN];
int dp[MAXN];

int tim = 1;
int n;

void path(int x) {
	if (vis[x] == tim)
		return;
	
	if (del[x] > 0) {
		dp[x] = 0;
		return;
	}
	
	vis[x] = tim;
	dp[x] = 1;
	
	for (int a : v[x]) {
		path(a);
		dp[x] = max(dp[x], 1+dp[a]);
	}
}

void updateDp() {
	tim++;
	
	for (int i=1; i<=n; i++)
		path(i);
}

int solve(int k) {
	vector<int> p;
	
	updateDp();
	
	int l = 0;
	int st = 1;
	
	for (int i=1; i<=n; i++) {
		if (dp[i] > l) {
			l = dp[i];
			st = i;
		}
	}
	
	if (k == 0)
		return l;
	
	p.push_back(st);
	
	while (dp[p.back()] > 1) {
		int next = -1;
		
		for (int a : v[p.back()]) {
			if (del[a] > 0)
				continue;
			if (dp[a] == dp[p.back()]-1) {
				next = a;
				break;
			}
		}
		
		p.push_back(next);
	}
	
	int res = l;
	
	for (int a : p) {
		del[a]++;
		res = min(res, solve(k-1));
		del[a]--;
	}
	
	return res;
}

int main() {
	int m, k, a, b;
	scanf("%d%d%d", &n, &m, &k);
	
	for (int i=0; i<m; i++) {
		scanf("%d%d", &a, &b);
		v[a].push_back(b);
	}
	
	printf("%d\n", solve(k));
	
	return 0;
}