#include<cstdio>
#include<vector>
#include<cstring>
using namespace std;
FILE*in=fopen("cuplaj.in","r");
FILE*out=fopen("cuplaj.out","w");
int n,m,e,i,j,x,y,ct,ctt;
vector<int> v[10004];
int r[10004],l[10004];
bool b[10004];
bool cuplaj(int nod)
{
    if(b[nod]==1)
    {
        return 0;
    }
    b[nod]=1;
    for(auto t:v[nod])
    {
        if(l[t]==0)
        {
            l[t]=nod;
            r[nod]=t;
            return 1;
        }
    }
    for(auto t:v[nod])
    {
        if(cuplaj(l[t])==1)
        {
            l[t]=nod;
            r[nod]=t;
            return 1;
        }
    }
    return 0;
}
int main()
{
    fscanf(in,"%d%d%d",&n,&m,&e);
    for(i=1;i<=e;i++)
    {
        fscanf(in,"%d%d",&x,&y);
        v[x].push_back(y);
    }
    while(true)
    {
        ctt=ct;
        memset(b,0,sizeof(b));
        for(i=1; i<=n; i++)
        {
            if(r[i]==0)
            {
                if(cuplaj(i)==1)
                {
                    ct++;
                }
            }
        }
        if(ctt==ct)
        {
            break;
        }
    }
    fprintf(out,"%d\n",ct);
    for(i=1;i<=n;i++)
    {
        if(r[i]!=0)
        {
            fprintf(out,"%d %d\n",i,r[i]);
        }
    }
}