#include <bits/stdc++.h>

using namespace std;

FILE *fin = fopen("cuplaj.in", "r");
FILE *fout = fopen("cuplaj.out", "w");

#define BUF 1 << 17
int pos = BUF;
char buf[BUF];

inline char next()  {
    if(pos == BUF)
        fread(buf, 1, BUF, fin), pos = 0;
    return buf[pos++];
}

inline int read()  {
    int x = 0;
    char ch = next();
    while(!isdigit(ch))
        ch = next();
    while(isdigit(ch))
        x = x * 10 + ch - '0', ch = next();
    return x;
}

#define MAX_N 10001

int N, M, E;
vector <int> G[MAX_N];

int u[MAX_N], v[MAX_N];
bool viz[MAX_N];

bool pairs(int nod)  {
    if(viz[nod])
        return 0;
    viz[nod] = 1;
    for(unsigned int i = 0;i < G[nod].size();i++)  {
        if(v[G[nod][i]] == 0)  {
            u[nod] = G[nod][i];
            v[G[nod][i]] = nod;
            return 1;
        }
    }
    for(unsigned int i = 0;i < G[nod].size();i++)  {
        if(pairs(v[G[nod][i]]))  {
            u[nod] = G[nod][i];
            v[G[nod][i]] = nod;
            return 1;
        }
    }
    return 0;
}

int main()  {
    N = read(), M = read(), E = read();
    for(int i = 0;i < E;i++)  {
        int x, y;
        x = read(), y = read();
        G[x].push_back(y);
    }
    bool ok = 1;
    while(ok)  {
        ok = 0;
        memset(viz, 0, sizeof(viz));
        for(int i = 1;i <= N;i++)
            if(!u[i])
                if(pairs(i))
                    ok = 1;
    }
    int nr = 0;
    for(int i = 1;i <= N;i++)
        if(u[i])
            nr++;
    fprintf(fout, "%d\n", nr);
    for(int i = 1;i <= N;i++)
        if(u[i])
            fprintf(fout, "%d %d\n", i, u[i]);
    fclose(fin);
    fclose(fout);
    return 0;
}