#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(!st[*it])
        {
            dr[nod]=*it; st[*it]=nod;
            return true;
        }
    for(it=L[nod].begin();it!=L[nod].end();++it)
        if(Cupleaza(st[*it]))
        {
            dr[nod]=*it; st[*it]=nod;
            return true;
        }
    return false;
}

int main()
{
    int x,y,M,ans=0,gata=0,i;
    freopen ("cuplaj.in","r",stdin);
    freopen ("cuplaj.out","w",stdout);
    scanf("%d%d%d", &n,&m,&M);
    while(M--)
    {
        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(!dr[i] && Cupleaza(i))
            {
                gata=0;
                //break;
            }
    }
    for(i=1;i<=n;++i) ans+=(dr[i]>0);
    printf("%d\n", ans);
    for(i=1;i<=n;++i)
        if(dr[i]) printf("%d %d\n", i,dr[i]);
    return 0;
}