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// Artur Kraska, II UWr

#include <algorithm>
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <vector>
#include <cmath>
#include <list>
#include <set>
#include <map>

#define forr(i, n)                  for(int i=0; i<n; i++)
#define FOREACH(iter, coll)         for(typeof(coll.begin()) iter = coll.begin(); iter != coll.end(); ++iter)
#define FOREACHR(iter, coll)        for(typeof(coll.rbegin()) iter = coll.rbegin(); iter != coll.rend(); ++iter)
#define lbound(P,R,PRED)            ({typeof(P) X=P,RRR=(R), PPP = P; while(PPP<RRR) {X = (PPP+(RRR-PPP)/2); if(PRED) RRR = X; else PPP = X+1;} PPP;})
#define testy()                     int _tests; scanf("%d", &_tests); FOR(_test, 1, _tests)
#define CLEAR(tab)                  memset(tab, 0, sizeof(tab))
#define CONTAIN(el, coll)           (coll.find(el) != coll.end())
#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 MP                          make_pair
#define PB                          push_back
#define deb(X)                      X;

#define M 1000000007
#define INF 1000000007

using namespace std;

int n, m, k, a, b;

struct elem
{
    vector <int> l;
    int odl;
    int gdzie;
    bool zly;
};
elem tab[1007];

int przelicz()
{
    int maks = 0, nr = -1;

    FORD(i, n, 1)
    {
        if(tab[i].zly)
            continue;
        tab[i].odl = 1;
        for(int j : tab[i].l)
            if(!tab[j].zly && tab[j].odl >= tab[i].odl)
            {
                tab[i].odl = tab[j].odl+1;
                tab[i].gdzie = j;
            }
        if(tab[i].odl > maks)
        {
            maks = tab[i].odl;
            nr = i;
        }
    }

    return nr;
}

int ruszaj(int ile)
{
    int p = przelicz();
    if(ile == 0)
    {
//        cout << "wynik to " << tab[p].odl << endl;
        return p == -1 ? 0 : tab[p].odl;
    }

    vector <int> v;
    v.PB(p);
    while(tab[p].odl > 1)
    {
        p = tab[p].gdzie;
        v.PB(p);
    }

    int res = 1007;
    for(int el : v)
    {
//        cout << "wywala " << el << endl;
        tab[el].zly = 1;
        res = min(res, ruszaj(ile-1));
//        cout << "przywraca " << el << endl;
        tab[el].zly = 0;
    }
    return res;
}

int main()
{
    scanf("%d %d %d", &n, &m, &k);
    forr(i, m)
    {
        scanf("%d %d", &a, &b);
        tab[a].l.PB(b);
    }

    int res = (k >= n ? 0 : ruszaj(k));
    printf("%d\n", res);

    return 0;
}