#include <cstdio>
#include <vector>
#define Nmax 10005

using namespace std;

int N,M,st[Nmax],dr[Nmax];
bool viz[Nmax];
vector <int> L[Nmax];

inline bool Cupleaza(int nod)
{
    if(viz[nod]) return false;
    viz[nod]=true;
    vector <int>::iterator it;
    for(it=L[nod].begin();it!=L[nod].end();++it)
        if(!dr[*it])
        {
            st[nod]=*it; dr[*it]=nod;
            return true;
        }
    for(it=L[nod].begin();it!=L[nod].end();++it)
        if(Cupleaza(dr[*it]))
        {
            st[nod]=*it; dr[*it]=nod;
            return true;
        }
    return false;
}

int main()
{
    int K,x,y,sol=0,gata=0,i;
    freopen ("cuplaj.in","r",stdin);
    freopen ("cuplaj.out","w",stdout);
    scanf("%d%d%d", &N,&M,&K);
    while(K--)
    {
        scanf("%d%d", &x,&y);
        L[x].push_back(y);
    }
    while(!gata)
    {
        gata=1;
        for(i=1;i<=N;++i) viz[i]=false;
        for(i=1;i<=N;++i)
            if(!st[i] && Cupleaza(i))
            {
                ++sol; gata=0;
            }
    }
    printf("%d\n", sol);
    for(i=1;i<=N;++i)
        if(st[i])
            printf("%d %d\n", i,st[i]);
    return 0;
}