#include <cstdio>
#include <bitset>
#include <vector>
#include <algorithm>

#define Nmax 10005
#define DIM 1000005

using namespace std;
vector<int> G[Nmax];
bitset<Nmax> used;
int N,M,K,L[Nmax],R[Nmax];
char buff[DIM];
int pz = DIM-1;

void citeste(int &A)
{
    A = 0;
    while('0' > buff[pz] || buff[pz] > '9')
        if(++pz == DIM)
            fread(buff,1,DIM,stdin),pz = 0;
    while('0' <= buff[pz] && buff[pz] <= '9')
    {
        A = A * 10 + buff[pz] - 48;
        if(++pz == DIM)
            fread(buff,1,DIM,stdin),pz = 0;
    }
}

void read()
{
    citeste(N);citeste(M);citeste(K);
    int a,b;
    for(int i = 1; i <= K; ++i)
    {
        citeste(a);citeste(b);
        G[a].push_back(b);
    }
}

bool cuplaj(int k)
{
    if(used[k] == 1)return false;
    used[k] = 1;
    for(vector<int>::iterator it = G[k].begin(); it != G[k].end(); ++it)
        if(!R[*it])
        {
            L[k] = *it;
            R[*it] = k;
            return true;
        }
    for(vector<int>::iterator it = G[k].begin(); it != G[k].end(); ++it)
        if(cuplaj(R[*it]))
        {
            L[k] = *it;
            R[*it] = k;
            return true;
        }
    return false;
}

int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    read();
    int ok = 1,ans = 0;
    while(ok)
    {
        ok = 0;
        used = 0;
        for(int i = 1; i <= N; ++i)
            if(!L[i] && cuplaj(i))
            {
                ok = 1;
                ++ans;
            }
    }
    printf("%d\n",ans);
    for(int i = 1; i <= N; ++i)
        if(L[i]) printf("%d %d\n",i,L[i]);
    return 0;
}