#include <fstream>
#include <vector>
#include <cstring>

using namespace std;

ifstream in("cuplaj.in");
ofstream out("cuplaj.out");

int n, m, edgeCount;
vector<int> edges[10001];
int l[10001], r[10001];
bool tk[10001];

bool pairup(int node)
{
    if(tk[node])
        return false;
    tk[node]=true;
    for(auto i=edges[node].begin();i!=edges[node].end();i++)
        if(r[*i]==0)
        {
            r[*i]=node;
            l[node]=*i;
            return true;
        }
    for(auto i=edges[node].begin();i!=edges[node].end();i++)
        if(pairup(r[*i]))
        {
            r[*i]=node;
            l[node]=*i;
            return true;
        }
    return false;
}

int main() {

    in>>n>>m>>edgeCount;

    while(edgeCount)
    {
        edgeCount--;
        int x, y;
        in>>x>>y;
        edges[x].push_back(y);
    }

    bool changed=true;
    while(changed)
    {
        changed=false;
        memset(tk, false, sizeof(tk));
        for(int i=1;i<=n;i++)
            if(l[i]==0)
                changed |= pairup(i);
    }

    int k=0;
    for(int i=1;i<=n;i++)
        if(l[i]>0)
            k++;

    out<<k<<'\n';

    for(int i=1;i<=n;i++)
        if(l[i]!=0)
            out<<i<<' '<<l[i]<<'\n';

    return 0;
}