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#include <bits/stdc++.h>


#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define VAR(v, i) __typeof(i) v=(i)
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define all(v) (v).begin(),(v).end()

#define PII pair<int,int>
#define mp make_pair
#define st first
#define nd second
#define pb push_back
#define lint long long int
#define VI vector<int>

#define debug(x) {cout <<#x <<" = " <<x <<endl; }
#define debug2(x,y) {cerr <<#x <<" = " <<x << ", "<<#y<<" = "<< y <<endl; } 
#define debug3(x,y,z) {cerr <<#x <<" = " <<x << ", "<<#y<<" = "<< y << ", " << #z << " = " << z <<endl; } 
#define debugv(x) {{cout <<#x <<" = "; FORE(itt, (x)) cerr <<*itt <<", "; cerr <<endl; }}
#define debugt(t,n) {{cerr <<#t <<" = "; FOR(it,0,(n)) cerr <<t[it] <<", "; cerr <<endl; }}

#define make( x) int (x); scanf("%d",&(x));
#define make2( x, y) int (x), (y); scanf("%d%d",&(x),&(y));
#define make3(x, y, z) int (x), (y), (z); scanf("%d%d%d",&(x),&(y),&(z));
#define make4(x, y, z, t) int (x), (y), (z), (t); scanf("%d%d%d%d",&(x),&(y),&(z),&(t));
#define makev(v,n) VI (v); FOR(i,0,(n)) { make(a); (v).pb(a);} 
#define IOS ios_base::sync_with_stdio(0)
#define HEAP priority_queue

#define read( x) scanf("%d",&(x));
#define read2( x, y) scanf("%d%d",&(x),&(y));
#define read3(x, y, z) scanf("%d%d%d",&(x),&(y),&(z));
#define read4(x, y, z, t) scanf("%d%d%d%d",&(x),&(y),&(z),&(t));
#define readv(v,n) FOR(i,0,(n)) { make(a); (v).pb(a);}
#define jeb() fflush(stdout);

using namespace std;
const int max_n = 3e5 + 5;

int n, m, k;
VI g[305];
VI og[305];

int active[305];
int dp[305];
int prv[305];
int ans;

int get_ans() {
	int lans = 0;
	FOR(j,0,n) {
		if (active[j] == 0) {
			dp[j] = 0;
		} else {
			dp[j] = 1;
			FORE(u, og[j]) {
				dp[j] = max(dp[j], dp[*u] + 1);
			}
			lans = max(lans, dp[j]);
			if (lans >= ans) return ans;
		}
	}
	if (lans >= ans) return ans;
	ans = lans;
	return lans;
}

VI get_longest_path() {
	FOR(i,0,n) {
		prv[i] = -1;
	}
	int lans = 0;
	int dla = -1;
	FOR(j,0,n) {
		if (active[j] == 0) {
			dp[j] = 0;
		} else {
			dp[j] = 1;
			FORE(u, og[j]) {
				if (active[*u] && dp[*u]+1 > dp[j]) {
					dp[j] = dp[*u] + 1;
					prv[j] = *u;
				}
			}
			if (dp[j] > lans) {
				lans = dp[j];
				dla = j;	
			}
		}
	}
	VI ja;
	while (dla!=-1) {
		ja.pb(dla);
		dla = prv[dla];
	}
	return ja;
}

void smutal() {
	FOR(i,0,n) active[i] = 1;
	ans = n;	
	VI my_path1 = get_longest_path();
	ans = my_path1.size();
	if (k >= 1) {
		FOR(i1,0,my_path1.size()) {
			int v1 = my_path1[i1];
			active[v1] = 0;
			VI my_path2 = get_longest_path();
			ans = min(ans, (int) my_path2.size());
			if (k >= 2) {
				FOR(i2,0,my_path2.size()) {
					int v2 = my_path2[i2];
					active[v2] = 0;
					VI my_path3 = get_longest_path();
					ans = min(ans, (int) my_path3.size());
					if (k >= 3) {
						FOR(i3,0,my_path3.size()) {
							int v3 = my_path3[i3];
							active[v3] = 0;
							VI my_path4 = get_longest_path();
							ans = min(ans, (int) my_path4.size());
							if (k >= 4) {
								FOR(i4,0,my_path4.size()) {
									int v4 = my_path4[i4];
									active[v4] = 0;
									ans = min(ans, get_ans());
									active[v4] = 1;
								}
							}
							active[v3] = 1;
						}	
					}
					active[v2] = 1;
				}
			}
			active[v1] = 1;
		}
	}
	printf("%d\n", ans);
}


void brutal() {
	ans = n;
	FOR(i,0,n) active[i] = 1;
	if (k == 0) ans = min(ans, get_ans());
	if (k >= 1) {
		FOR(i1,0,n) {
			active[i1] = 0;
			if (k == 1) ans = min(ans, get_ans());
			else {
				FOR(i2,i1+1,n) {
					active[i2] = 0;
					if (k == 2) ans = min(ans, get_ans());
					else {
						FOR(i3,i2+1,n) {
							active[i3] = 0;
							if (k == 3) ans = min(ans, get_ans());
							else {
								FOR(i4,i3+1,n) {
									active[i4] = 0;
									ans = min(ans, get_ans());
									active[i4] = 1;
								}
							}
							active[i3] = 1;
						}
					}
					active[i2] = 1;
				}
			}
			active[i1] = 1;
		}
	}
	printf("%d\n", ans);
}

int main() {
	read3(n, m, k);
	FOR(i,0,m) {
		make2(a, b); a--; b--;
		g[a].pb(b);
		og[b].pb(a);
	}
	if (n <= 65) {
		brutal();
		return 0;
	} else {
		smutal();
		return 0;
	}
	
}