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

queue<int> q;
int n,m,k;

vector<int> G[301];
pair<int, int> krawedzie[401];
void printG()
{
    cout<<"printing G: "<<endl;
    for(int i=1;i<=n;i++)
    {
        cout<<i<<":"<<endl;
        for(int j=0;j<G[i].size();j++)
        {
            cout<<G[i][j]<<" ";
        }
        cout<<endl;
    }
    
}
int rekur(int k, set<int> removed)
{
    vector<int> starting;
    int wejscia[301];
    for(int i=0;i<m;i++)
    {
        if(removed.find(krawedzie[i].first)==removed.end())
            wejscia[krawedzie[i].second]++;
    }
    int max_length=0;
    set<int> set_to_test;
    int path_length[301];
    
    set<int> paths[301];
    for(int i=0;i<=n;i++)
    {
        path_length[i]=1;
        paths[i].clear();
        wejscia[i]=0;
        starting.clear();
        
    }
    for(int i=1;i<=n;i++)
    {
        if(wejscia[i]==0 and removed.find(i)==removed.end())
        {
            starting.push_back(i);
            path_length[i]=1;
        }
    }
    
    set_to_test.clear();
    max_length=1;
    for(int i=0;i<starting.size();i++)
    {
        paths[starting[i]].insert(starting[i]);
        q.push(starting[i]);
    }
    while(!q.empty())
    {
        int actual = q.front();
        //printG();
        q.pop();
        for(int i=0;i<G[actual].size();i++)        
        {
            if(removed.find(G[actual][i])!=removed.end())
                continue;
            int sizeOfChild = paths[G[actual][i]].size();
            int mysize = paths[actual].size();
            //cout<<actual<<" "<<G[actual][i]<<endl;
            if(mysize+1>=sizeOfChild)
            {
                paths[G[actual][i]].insert(paths[actual].begin(), paths[actual].end());   
                paths[G[actual][i]].insert(G[actual][i]);
                q.push(G[actual][i]);
                path_length[G[actual][i]]=path_length[actual]+1;
                max_length = max(path_length[G[actual][i]],max_length);
            }
        }
    }
    
    if(k==0)
        return max_length;
    for(int i=1;i<=n;i++)
    {
        if(path_length[i]==max_length)
            set_to_test.insert(paths[i].begin(),paths[i].end());
    }
    //usuwanie elementóœ
    int best = 500;
    int result = -1;
    set<int>::iterator it;
    for (it=set_to_test.begin(); it!=set_to_test.end(); ++it)
    {
        removed.insert(*it);
        result = rekur(k-1,removed);
        //cout<<"removed "<<*it<<" result: "<<result<<endl;
        
        best=min(best, result);
        
        removed.erase(*it);
    }
    //cout<<k<<" "<<best<<endl;
    return best;
}

int main()
{
    int a,b;
    cin>>n>>m>>k;
    if(k>=n)
    {
        cout<<0<<endl;
        return 0;
    }
    for(int i=0;i<m;i++)
    {
        cin>>a>>b;
        krawedzie[i] = make_pair(a, b);
        //cout<<"pushing "<<b<<" to "<<a<<endl;
        G[a].push_back(b);
    }
    set<int>xd;
    //printG();
    cout<<rekur(k,xd);
    
    return 0;
}