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#include<bits/stdc++.h>
#define rep(i,k,n) for(ll i= (ll) k;i< (ll) n;i++)
#define all(v) (v).begin(), (v).end()
#define SZ(v) (ll)((v).size())
#define pb push_back
#define ft first
#define sd second
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const long long INF = 1e18L + 1;
const int IINF = 1e9 + 1;

using namespace std;

template<class TH> void _dbg(const char *sdbg, TH h){ cerr<<sdbg<<'='<<h<<endl; }
template<class TH, class... TA> void _dbg(const char *sdbg, TH h, TA... a) {
  while(*sdbg!=',')cerr<<*sdbg++;
  cerr<<'='<<h<<','; _dbg(sdbg+1, a...);
}

#ifdef LOCAL
#define DBG(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#else
#define DBG(...) (__VA_ARGS__)
#define cerr if(0)cout
#endif

const ll N = 3e2, K = 4;
ll n, m, k;
vector<ll> nei[N + 1];
ll pred[K + 1][N + 1], pth[N + 1];
bool alive[N + 1];

ll solve(ll dpth){
	rep(v, 1, n + 1){
		pth[v] = 1;
		pred[dpth][v] = 0;
	}
	ll l_pth = 0, pth_end = 0;
	rep(v, 1, n + 1){
		if(alive[v]){
			if(pth[v] > l_pth){
				l_pth = pth[v];
				pth_end = v;
			}
			for(auto& w : nei[v]){
				if(alive[w] and pth[w] < pth[v] + 1){
					pred[dpth][w] = v;
					pth[w] = pth[v] + 1;
				}
			}
		}
	}
	if(dpth == 0 or l_pth == 0){
		return l_pth;
	} else{
		ll pth_vert = pth_end, res = INF;
		while(pth_vert != 0){
			alive[pth_vert] = false;
			res = min(res, solve(dpth - 1));
			alive[pth_vert] = true;
			pth_vert = pred[dpth][pth_vert];
		}
		return res;
	}
}

int main()
{
#ifndef LOCAL
	ios_base::sync_with_stdio(0);
    cin.tie(0);
#endif
	cin >> n >> m >> k;
	rep(_, 0, m){
		ll u, v; cin >> u >> v;
		nei[u].pb(v);
	}
	rep(v, 1, n + 1){
		alive[v] = true;
	}
	cout << solve(k) << "\n";
    return 0;
}