1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<int, int> pii;

#define PB push_back
#define ST first
#define ND second


const int maxn = 320;
vector<int> v[maxn];
int n;
int d[maxn], val[maxn], p[maxn];
bool cur[maxn];

int rec(int k)
{
	for(int i=1; i <= n; i++)
		d[i] = 0;
	for(int i=1; i <= n; i++)
		if(cur[i] == false)
			for(int b : v[i])
				d[b]++;
	queue<int> q;
	for(int i=1; i <= n; i++)
	{
		if(cur[i])
			continue;
		if(d[i] == 0)
			q.push(i);
		val[i] = 1;
		p[i] = -1;
	}
	while(q.empty() == false)
	{
		int a = q.front();
		q.pop();
		for(int b : v[a])
		{
			if(cur[b])
				continue;
			d[b]--;
			if(d[b] == 0)
				q.push(b);
			if(val[a]+1 > val[b])
			{
				val[b] = val[a]+1;
				p[b] = a;
			}
		}
	}
	int maxd=0, maxi=0;
	for(int i=1; i <= n; i++)
	{
		if(cur[i])
			continue;
		if(val[i] > maxd)
		{
			maxd = val[i];
			maxi = i;
		}
	}
	if(maxd == 0)
		return 0;
	if(k == 0)
		return maxd;
	vector<int> t;
	int a = maxi;
	t.PB(a);
	while(p[a] != -1)
	{
		a = p[a];
		t.PB(a);
	}
	int res=maxd;
	for(int b : t)
	{
		cur[b] = true;
		int x = rec(k-1);
		//cout << b << " " << x << endl;
		res = min(res, x);
		cur[b] = false;
	}
	return res;
}

int main()
{
	ios_base::sync_with_stdio(0);
	int m, k;
	cin >> n >> m >> k;
	while(m--)
	{
		int a, b;
		cin >> a >> b;
		v[a].PB(b);
	}
	cout << rec(k) << "\n";
	
	return 0;
}