#include <bits/stdc++.h>

#define RIGHT 0
#define LEFT  1

class BipartiteMatching {
public:
    BipartiteMatching(std::vector<std::vector <int>>& graph) : count(0) {
        for (int i=0; i<2; ++i) pair[i].resize(graph.size(), -1);
        seen.resize(graph.size(), 0);
        bool bFlag = 1;
        while (bFlag) {
            bFlag = 0;
            for (int i=0; i<graph.size(); ++i)
                seen[i] = 0;
            for (int i=0; i<graph.size(); ++i)
                if (pair[RIGHT][i] == -1 && pairUp(i, graph))
                    bFlag = 1, ++ count;
        }
    }
    int size() const {return count;}
    int operator[] (int idx) {return pair[RIGHT][idx];}
protected:
    int count;
    std::vector <int> pair[2];
    std::vector <bool> seen;
    bool pairUp(int vertex, std::vector<std::vector <int>>& graph) {
        if (seen[vertex]) return false;
        seen[vertex] = 1;
        for (auto adj:graph[vertex])
            if (pair[LEFT][adj] == -1 || pairUp(pair[LEFT][adj], graph))
                {pair[LEFT][adj] = vertex; pair[RIGHT][vertex] = adj; return true;}
        return false;
    }
};

int N, M, E;
std::vector<std::vector <int>> graph;

inline void addEdge(int x, int y) {
    graph[x].push_back(y);
}

std::ifstream input ("cuplaj.in");
std::ofstream output("cuplaj.out");

void readInput() {
    input >> N >> M >> E;
    graph.resize(std::max(N, M), std::vector <int> ());
    for (int i=0, x, y; i<E; ++i)
        input >> x >> y, addEdge(--x, --y);
}

void solveInput() {
    BipartiteMatching match(graph);
    output << match.size() << '\n';
    for (int i=0; i<N; ++i)
        if (match[i] != -1)
            output << i+1 << ' ' << match[i]+1 << '\n';
}

int main()
{
    readInput();
    solveInput();

    return 0;
}