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
#include <cstdio>
#include <cassert>
#include <set>
#include <algorithm>
#include <cstring>
#include <vector>
using std::vector;

const int M = 313;

vector<int> v[M], cc, a, b;
vector<int> zo;
int ret;

int calc(int n) {
	a = b = vector<int>(n+1);
	for (int i = n; i >= 0; i--) {
		for (int j = 0; j < v[i].size(); j++) 
			if (zo[v[i][j]] >= 0) {
				int x = a[v[i][j]]+1;
				if (a[i] < x) {
					a[i] = x;
					b[i] = v[i][j];
				}
			}
	}
	cc.clear();
	int i = 0;
	while(a[i]) {
	  i = b[i];
		cc.push_back(i);
	}
	return a[0];
}

void go(int n, int k) {
  //printf("%d %d\n", n, k);
	if (!k) {
	  ret = std::min(ret, calc(n));
		return;
	}
	calc(n);
	vector<int> my = cc;
	for(int i = 0; i < my.size(); i++) {
		if(!zo[my[i]]) {
		  zo[my[i]] = -1;
			go(n, k-1);
		  zo[my[i]] = 0;
		}
		zo[my[i]]++;
	}
	for (int i = 0; i < my.size(); i++) {
	  zo[my[i]]--;
	}
}

int main() {
	int n, m, k;
	scanf("%d %d %d", &n, &m, &k);
	for (int i = 1; i<=n; i++) v[0].push_back(i);

	vector<std::pair<int, int> > tt;
	for (int i = 1; i <= n; i++) for (int j = i+1; j <= n; j++)
		tt.push_back(std::make_pair(i, j));

	//srand(time(0));

	for (int i = 0; i < m; i++) {
	  int a,b;
		
		/*int u = rand() % tt.size();
		a = tt[u].first;
		b = tt[u].second;
		tt[u] = tt.back();
		tt.pop_back();
		*/
		scanf("%d %d",&a,&b);

		v[a].push_back(b);
	}

	zo = vector<int>(n+1);
	ret = calc(n);
  go(n, k);
	printf("%d\n", ret);
}