#include <cstdio>
#include <vector>
#define NMax 10000
using namespace std;

vector<int> a[NMax+1];
int viz[NMax+1];
int st[NMax+1];
int dr[NMax+1];
int res;

int Cupleaza(int x)
{
    if(viz[x]) return 0;
    viz[x] = 1;

    int i,y;
    for(i = 0; i < a[x].size(); ++i)
    {
        y = a[x][i];
        if(!dr[y])
        {
            dr[y] = x;
            st[x] = y;
            return 1;
        }
    }

    for(i = 0; i < a[x].size(); ++i)
    {
        y = a[x][i];
        if(Cupleaza(dr[y]))
        {
            dr[y] = x;
            st[x] = y;
            return 1;
        }
    }

    return 0;
}

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

    int i,x,y,stop,N,M,E;

    fscanf(fin,"%d %d %d",&N,&M,&E);
    for(i = 1; i <= E; ++i)
    {
        fscanf(fin,"%d %d",&x,&y);
        a[x].push_back(y);
    }

    stop = 1;
    while(stop)
    {
        stop = 0;
        for(i = 1; i <= N; ++i) viz[i] = 0;
        for(i = 1; i <= N; ++i)
        if(!st[i] && Cupleaza(i))
        {
            ++res;
            stop = 1;
        }
    }

    fprintf(fout,"%d\n",res);
    for(i = 1; i <= N; ++i)
    if(st[i]) fprintf(fout,"%d %d\n",i,st[i]);


return 0;
}