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#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int N, M, K;
vector<vector<int>> deps;

int solve(int k, const set<int>& without) {
    vector<int> length(N+1);
    vector<int> through(N+1);
    
    int longest = 0;
    
    for (int i = N; i >= 1; --i) {
        if (without.count(i))
            continue;
            
        int len = 1;
        int thr = 0;
        for (int ne : deps[i]) {
            if (length[ne] + 1 >= len) {
                len = length[ne] + 1;
                thr = ne;
            }
        }
        length[i] = len;
        through[i] = thr;
        
        if (length[i] > length[longest]) {
            longest = i;
        }
    }
    
    if (k == 0)    
        return length[longest];
        
    
    int ans = length[longest];
    
    for (int i = longest; i!=0; i = through[i]) {
        set<int> wc(without);
        wc.insert(i);
        int subans = solve(k-1, wc);
        if (subans < ans)
            ans = subans;
    } 
        
    return ans;
}

int main() {
    cin >> N >> M >> K;
    
    deps.resize(N+1);
    
    for (int i = 0; i < M; ++i) {
        int x, y;
        cin >> x >> y;
        deps[x].push_back(y);
    }
    
    cout << solve(K, {});
    
    return 0;
}