#include <cstdio>
#include <vector>
#include <bitset>
using namespace std;
FILE *f=fopen("cuplaj.in","r");
FILE *g=fopen("cuplaj.out","w");
int N,M,K;
vector<int> G[10005];
int L[10005];
int R[10005];
bitset<10005> U;
bool pairup(int x)
{
    if(U[x])
        return 0;
    U[x]=1;
    for(auto it:G[x])
        if(R[it]==0||pairup(R[it]))
            {L[x]=it,R[it]=x;return 1;}
    return 0;
}
int main()
{
    fscanf(f,"%d%d%d",&N,&M,&K);
    for(int i=1;i<=K;i++)
    {
        int x,y;
        fscanf(f,"%d%d",&x,&y);
        G[x].push_back(y);
    }
    bool ok=1;
    int c=0;
    while(ok)
    {
        ok=0;
        U.reset();
        for(int i=1;i<=N;i++)
            if(L[i]==0)
                if(pairup(i))
                    c++,ok=1;
    }
    fprintf(g,"%d\n",c);
    for(int i=1;i<=N;i++)
        if(L[i])
            fprintf(g,"%d %d\n",i,L[i]);
    fclose(f);
    fclose(g);
    return 0;
}