#pragma GCC optimize("O3,unroll-loops,fast-math")
#include<bits/stdc++.h>
#define pb push_back
using namespace std;
const int dm=1e4+55;
int n,m,e,x,y,sol,st[dm],dr[dm];
bitset<dm>vz;
vector<int>a[dm];
bool cup(int x)
{
    if(vz[x])return 0;
    vz[x]=1;
    for(auto it:a[x])
        if(dr[it]==0)
    {
        st[x]=it;
        dr[it]=x;
        sol++;
        return 1;
    }

    for(auto it:a[x])
        if(cup(dr[it]))
    {
        st[x]=it;
        dr[it]=x;
        return 1;
    }
    return 0;
}
int main()
{
    ifstream fin("cuplaj.in");
    ofstream fout("cuplaj.out");
    fin>>n>>m>>e;
    while(e--)
    {
        fin>>x>>y;
        a[x].pb(y);
    }
    bool cuplat=1;
    while(cuplat)
    {
        vz.reset();
        cuplat=0;
        for(int i=1;i<=n; ++i)
            if(st[i]==0)cuplat|=cup(i);
    }
    fout<<sol<<'\n';
    for(int i = 1;i<=n; ++i)
        if(st[i])fout<<i<<" "<<st[i]<<'\n';
    return 0;

}