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#include <cstdio>
#include <vector>

using namespace std;

int n, m, k, u, v, result=10000, dist[305], nextv[305], longest[305], start[305];
vector<int> graph[305], paths[4];

bool disabled[305];

void update(int x) {
	for (int i = x; i > 0; i--) {
		if (disabled[i])
			continue;
		dist[i] = 0;
		for (int v : graph[i]) {
			if (disabled[v])
				continue;
			if (dist[v] >= dist[i]) {
				dist[i] = dist[v] + 1;
				nextv[i] = v;
			}
		}
		longest[i] = longest[i+1];
		start[i] = start[i+1];
		if (dist[i] > longest[i]) {
			longest[i] = dist[i];
			start[i] = i;
		}
	}
}

void compute(int x, int to_delete) {
	//fill(dist, dist+n+1, 0);
	//fill(nextv, nextv+n+1, 0);
	disabled[x] = true;
	update(x);

	if (to_delete == 0) {
		result = min(result, longest[1]);
	} else {
		auto &path = paths[k - to_delete];
		path.clear();
		v = start[1];
		while (v != 0) {
			path.push_back(v);
			v = nextv[v];
		}

		for (auto v : path) {
			compute(v, to_delete - 1);
		}
	}

	disabled[x] = false;
	update(x);
}


int main() {
	scanf("%d%d%d", &n, &m, &k);

	while (m--) {
		scanf("%d%d", &u, &v);
		graph[u].push_back(v);
	}
	
	if (n==k) {
		printf("0\n");
		return 0;
	}

	compute(n+1, k);

	printf("%d\n", result+1);
}