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#include<bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = a; i <= b; i++)
#define REP(i, a) FOR(i, 0, a - 1)
#define ST first
#define ND second
#define V vector
#define RS resize
#define EB emplace_back
#define ALL(a) a.begin(), a.end()
#define S(a) (int)a.size()

template<class T> void db(T a) { cerr << a; }
template<class L, class R> void db(pair<L, L> a) { cerr << "(" << a.ST << ", " << a.ND << ")"; }
template<class T> void db(V<T> v) { cerr << "{"; REP(i, S(v)) cerr << (i != 0 ? ", " : ""), db(v[i]); cerr << "}"; }
template<class T> void dump(const char *s, T a) { cerr << s << ": "; db(a); cerr << "\n"; }
template<class T, class... TS> void dump(const char *s, T a, TS... x)
{ while(*s != ',') cerr<< *s++; cerr << ": "; db(a); dump(s + 1, x...); }

#ifdef DEBUG
#define DB(...) dump(#__VA_ARGS__, __VA_ARGS__); 
#else
#define DB(...)
#endif

using LL = long long;
using PII = pair<int, int>;
using VI = V<int>;
using VLL = V<LL>;
using VVI = V<VI>;
using VPII = V<PII>;

VVI g;
VI used;
V<bool> removed;
VI dp;

int called = 0;
int to_add;
int calc()
{
    int ans = 0;
    called++;
    for(int i = S(used) - 1; i >= 0; i--)
    {
        used[i] = -1;
        dp[i] = 0;
        if(removed[i])
            continue;

        for(int x : g[i])
            dp[i] = max(dp[i], dp[x]);

        for(int x : g[i])
        {
            if(dp[i] == dp[x] && used[i] == -1)
                used[i] = x;
        }

        dp[i]++;
        ans = max(ans, dp[i]);
    }
    return ans;
}

int backtrack(int rec)
{
    if(rec == 0)
        return calc();

    int mx = calc();
    int n = S(dp);

    V<bool> added(n);
    VI s;

    REP(i, n) if(dp[i] == mx)
    {
        int p = i;
        while(p != -1)
        {
            s.EB(p);
            p = used[p];
        }
        break;
    }

    int best = 1e9;
    for(int x : s)
    {
        removed[x] = 1;
        best = min(best, backtrack(rec - 1));
        removed[x] = 0;

        if(called * to_add > 200000000)
            break;
    }

    return best;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int n, m, k;
    cin >> n >> m >> k;
    
    g.RS(n);
    used.RS(n);
    dp.RS(n);
    removed.RS(n);
    REP(i, m)
    {
        int a, b;
        cin >> a >> b;
        g[a - 1].EB(b - 1);
    }

    to_add = n + m;
    cout << backtrack(k) << "\n";
    return 0;
}