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#include <cstdio>
#include <vector>
#include <algorithm>

const int max_n = 401;

int n, m, k;
std::vector<int> out[max_n];
int deleted[max_n];
int prev_node[max_n];
int dp[max_n];

std::pair<int, int> compute_worst_path() {
	int curr_max = 0;
	int curr_index = -1;
	for (int i = 0; i < n; ++i) {
		dp[i] = 1;
		prev_node[i] = -1;
		for (int j = 0; j < out[i].size(); ++j) {
			if (deleted[out[i][j]] == 0 && dp[i] < 1 + dp[out[i][j]]) {
				prev_node[i] = out[i][j];
				dp[i] = 1 + dp[out[i][j]];
			}
		}
	    if (curr_max < dp[i]) {
			curr_max = dp[i];
			curr_index = i;
		}
	}
	return std::pair<int, int>(curr_max, curr_index);
}

int gogogo(int gl) {
	std::pair<int, int> ret = compute_worst_path();
	if (gl == 0) {
		return ret.first;
	}
	else {
		std::vector<int> candidates;
		while (ret.second != -1) {
			candidates.push_back(ret.second);
			ret.second = prev_node[ret.second];
		}
		int ret = n;
		for (int a = 0; a < candidates.size(); ++a) {
			int candidate = candidates[a];
			deleted[candidate] = 1;
			int curr_ret = gogogo(gl - 1);
			if (curr_ret < ret) ret = curr_ret;
			deleted[candidate] = 0;
		}
		return ret;
	}
}

int main() {
	scanf("%d %d %d", &n, &m, &k);
	for (int i = 0; i < n; ++i) {
		deleted[i] = 0;
	}
	for (int i = 0; i < m; ++i) {
		int x, y;
		scanf("%d %d", &x, &y);
		--x; --y;
		out[y].push_back(x);
	}
	if (k < n) {
		printf("%d\n", gogogo(k));
	} else {
		printf("0\n");
	}
	return 0;
}