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#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,b) for (int i = (a); i <= (b); ++i)
#define REPD(i,a,b) for (int i = (a); i >= (b); --i)
#define FORI(i,n) REP(i,1,n)
#define FOR(i,n) REP(i,0,int(n)-1)
#define mp make_pair
#define pb push_back
#define pii pair<int,int>
#define vi vector<int>
#define ll long long
#define SZ(x) int((x).size())
#define DBG(v) cerr << #v << " = " << (v) << endl;
#define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define fi first
#define se second

const int N = 444;

int n;
int res;
bool bad[N];
vector<int> g[N];
int dp[N];

void go(int k) {
	//printf("go %d [", k);
	//FOR(i,n) if (bad[i]) printf("%d ", i);
	//printf("]\n");
	int cur = -1, who = -1;
	for (int i=n-1; i>=0; i--) {
		if (bad[i]) continue;
		dp[i]=1;
		FOR(j,SZ(g[i])) if (!bad[g[i][j]]) dp[i] = max(dp[i], dp[g[i][j]]+1);
		if (dp[i] > cur) {
			cur = dp[i];
			who = i;
		}
	}
	if (who == -1) {
		res = 0;
		return;
	}
	if (k == 0) {
		res = min(res, cur);
		return;
	}
	//printf("%d -- %d\n", k, who);
	vi path(1, who);
	while (dp[who]>1) {
		//printf("%d\n", who);
		FOR(j,SZ(g[who])) if (!bad[g[who][j]] && dp[g[who][j]]+1 == dp[who]) {
			who = g[who][j];
			break;
		}
		path.pb(who);
	}
	FOR(i,SZ(path)) {
		bad[path[i]] = 1;
		go(k-1);
		bad[path[i]] = 0;
	}
}

int main() {
	int m,k;
	scanf("%d%d%d", &n, &m, &k);
	FOR(i,m) {
		int a,b;
		scanf("%d%d", &a, &b);
		a--; b--;
		g[a].pb(b);
	}
	res = n;
	go(k);
	printf("%d\n", res);
	return 0;
}