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#include <bits/stdc++.h>
using namespace std;

#define REP(i, x) for( int i = 0; i < x; i++ )
#define FOR(i, x) for( int i = 1; i <=x; i++ )
#define FORALL(it, x) for(__typeof(x.begin()) it = x.begin(); it != x.end(); it++)
#define PB push_back

typedef vector<int> VI;
typedef vector<VI> VVI;

const int MAX_K = 5;
const int MAX_N = 307;

int wynik = MAX_N;

int longest_path[MAX_K][MAX_N];
int father[MAX_K][MAX_N];
bool blocked[MAX_N];

VVI graph(MAX_N);

int n, k;

void wczytaj(){
    int m;
    cin >> n >> m >> k;
    REP(i, m){
        int x, y;
        cin >> x >> y;
        graph[y].PB(x);
    }
}

void rozw(int k){
    int ktory = 0;
    FOR(i, n) if( !blocked[i] ){
        longest_path[k][i] = 1;
        father[k][i] = 0;
        FORALL(it, graph[i]) if( !blocked[*it] )
            if( longest_path[k][*it] + 1 > longest_path[k][i] ){
                longest_path[k][i] = longest_path[k][*it] + 1;
                father[k][i] = *it;
                if( longest_path[k][i] > longest_path[k][ktory] )
                    ktory = i;
            }
        if( longest_path[k][i] > longest_path[k][ktory] )
            ktory = i;
    }
    if( k == 0 ) wynik = min(wynik, longest_path[k][ktory]);
    else {
        int dl = longest_path[k][ktory];
        int pod = 0;
        while(ktory){
            if( pod < wynik ){
                blocked[ktory] = 1;
                rozw(k-1);
                blocked[ktory] = 0;
            }
            ktory = father[k][ktory];
            pod++;
        }
    }
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    wczytaj();
    rozw(k);
    cout << wynik << endl;
    return 0;
}