#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define ar array
#define vt vector
#define pq priority_queue
#define pu push
#define pub push_back
#define em emplace
#define emb emplace_back

#define all(x) x.begin(), x.end()
#define allr(x) x.rbegin(), x.rend()
#define allp(x, l, r) x.begin() + l, x.begin() + r
#define len(x) (int)x.size()

using namespace std;
using namespace __gnu_pbds;

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template <class T, size_t N>
void re(array <T, N>& x);
template <class T> 
void re(vt <T>& x);

template <class T> 
void re(T& x) {
    cin >> x;
}

template <class T, class... M> 
void re(T& x, M&... args) {
    re(x); re(args...);
}

template <class T> 
void re(vt <T>& x) {
    for(auto& it : x)
        re(it);
}

template <class T, size_t N>
void re(array <T, N>& x) {
    for(auto& it : x)
        re(it);
}

template <class T, size_t N>
void wr(array <T, N> x);
template <class T> 
void wr(vt <T> x);

template <class T> 
void wr(T x) {
    cout << x;
}

template <class T, class ...M>  void wr(T x, M... args) {
    wr(x), wr(args...);
}

template <class T> 
void wr(vt <T> x) {
    for(auto it : x)
        wr(it, ' ');
}

template <class T, size_t N>
void wr(array <T, N> x) {
    for(auto it : x)
        wr(it, ' ');
}


inline void Open(const string Name) {
    #ifndef ONLINE_JUDGE
        (void)!freopen((Name + ".in").c_str(), "r", stdin);
        (void)!freopen((Name + ".out").c_str(), "w", stdout);
    #endif
}

struct HopcroftKarp {
    int n;
    vt <int> l, r;
    vt <bool> vis;
    vt <vt <int>> adj;

    HopcroftKarp() {}
    HopcroftKarp(int _n) {
        n = _n;
        adj.resize(n);
        vis.resize(n, false);
        l.resize(n, -1);
        r.resize(n, -1);
    }

    void init(int _n) {
        n = _n;
        adj.resize(n);
        vis.resize(n, false);
        l.resize(n, -1);
        r.resize(n, -1);
    }

    void add_edge(int u, int v) {
        adj[u].emb(v);
    }

    bool pairup(int u) {
        /* if we already visited the node before it means we already tried all options for it */
        if (vis[u]) {
            return false;
        }

        /* if for an edge we can have a pair we make the pair */
        vis[u] = true;
        for (int v : adj[u]) {
            if (r[v] == -1) {
                l[u] = v;
                r[v] = u;
                return true;
            }
        }

        /* if for the u' edge that pairs with v, we have another match 
        then we can make a match with u and v 
        */
        for (int v : adj[u]) {
            if (pairup(r[v])) {
                l[u] = v;
                r[v] = u;
                return true;
            }
        }

        return false;
    }

    int maximum_matching() {
        int ans = 0;
        /* we repeat the process till we cannot have any matches */
        for (int change = 1; change; ) {
            change = 0; 
            fill(all(vis), false);
            for(int u = 0; u < n; u++) 
                if(l[u] == -1) {
                    /* if we have one match we repeat the process again */
                    change |= pairup(u);
                }
        }

        for (int u = 0; u < n; ++u)
            ans += (l[u] != -1);
        return ans;
    }
};

void solve() {
    int n, m, e; re(n, m, e);
    HopcroftKarp F(n);
    for (int i = 0; i < e; ++i) {
        int u, v; re(u, v);
        --u, --v;
        F.add_edge(u, v);
    }

    wr(F.maximum_matching(), '\n');
    for (int i = 0; i < n; ++i)
        if (F.l[i] != -1) {
            wr(i + 1, ' ', F.l[i] + 1, '\n');
        }
}

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

    Open("cuplaj");

    int t = 1;
    for(;t;t--) {
        solve();
    }
    
    return 0;
}