#include <bits/stdc++.h>

using namespace std;
const int NR = 1e4 + 14;
const int MOD = 666013;


int n, m, e;
vector<int> v[NR];
int c[NR], viz[NR], r[NR], cnt;

bool match(int nod) {
    if (viz[nod]) {
        return false;
    }
    viz[nod] = 1;
    for (auto it : v[nod]) {
        if (!r[it]) {
            c[nod] = it;
            r[it] = nod;
            return true;
        }
    }
    for (auto it : v[nod]) {
        if (match(r[it])) {
            c[nod] = it;
            r[it] = nod;
            return true;
        }
    }
    return false;
}

class InParser {
private:
    FILE *fin;
    char *buff;
    int sp;

    char read_ch() {
        ++sp;
        if (sp == 4096) {
            sp = 0;
            fread(buff, 1, 4096, fin);
        }
        return buff[sp];
    }

public:
    InParser(const char *nume) {
        fin = fopen(nume, "r");
        buff = new char[4096]();
        sp = 4095;
    }

    InParser &operator>>(int &n) {
        char c;
        while (!isdigit(c = read_ch()) && c != '-');
        int sgn = 1;
        if (c == '-') {
            n = 0;
            sgn = -1;
        } else {
            n = c - '0';
        }
        while (isdigit(c = read_ch())) {
            n = 10 * n + c - '0';
        }
        n *= sgn;
        return *this;
    }

    InParser &operator>>(long long &n) {
        char c;
        n = 0;
        while (!isdigit(c = read_ch()) && c != '-');
        long long sgn = 1;
        if (c == '-') {
            n = 0;
            sgn = -1;
        } else {
            n = c - '0';
        }
        while (isdigit(c = read_ch())) {
            n = 10 * n + c - '0';
        }
        n *= sgn;
        return *this;
    }
};

struct OutParser {
    FILE *fout;
    char *buff;
    int sp;

    void write_ch(char ch) {
        if (sp == 50000) {
            fwrite(buff, 1, 50000, fout);
            sp = 0;
            buff[sp++] = ch;
        } else {
            buff[sp++] = ch;
        }
    }

    OutParser(const char *name) {
        fout = fopen(name, "w");
        buff = new char[50000]();
        sp = 0;
    }

    ~OutParser() {
        fwrite(buff, 1, sp, fout);
        fclose(fout);
    }

    OutParser &operator<<(int vu32) {
        if (vu32 <= 9) {
            write_ch(vu32 + '0');
        } else {
            (*this) << (vu32 / 10);
            write_ch(vu32 % 10 + '0');
        }
        return *this;
    }

    OutParser &operator<<(char ch) {
        write_ch(ch);
        return *this;
    }

    OutParser &operator<<(const char *ch) {
        while (*ch) {
            write_ch(*ch);
            ++ch;
        }
        return *this;
    }
};


signed main() {

    InParser in("cuplaj.in");
    OutParser out("cuplaj.out");
    int x, y;
    in >> n >> m >> e;
    while (e--) {
        in >> x >> y;
        v[x].emplace_back(y);
    }
    bool change = true;
    while (change) {
        change = false;
        for (int i = 1; i <= n; ++i) {
            viz[i] = 0;
        }
        for (int i = 1; i <= n; ++i) {
            if (!c[i]) {
                change |= match(i);
            }
        }
    }
    for (int i = 1; i <= n; ++i) {
        cnt += bool(c[i]);
    }
    out << cnt << '\n';
    for (int i = 1; i <= n; ++i) {
        if (c[i]) {
            out << i << ' ' << c[i] << '\n';
        }
    }
    return 0;
}