#include <bits/stdc++.h>

using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int n,m,e,ans,x,y;
int val[10005];
bool tried[10005];
vector<int>nod[10005];
bool try_to_change(int pos)
{
    if(tried[pos])return false;
    tried[pos]=true;
    for(int i=0;i<nod[pos].size();i++)
        if(val[nod[pos][i]]==0)
        {
            val[nod[pos][i]]=pos;
            return true;
        }
    for(int i=0;i<nod[pos].size();i++)
        if(val[nod[pos][i]]!=pos && try_to_change(val[nod[pos][i]]))
        {
            val[nod[pos][i]]=pos;
            return true;
        }
    return false;
}
int main()
{
    fin>>n>>m>>e;
    for(int i=1;i<=e;i++)
    {
        fin>>x>>y;
        nod[x].push_back(y);
    }
    for(int i=1;i<=n;i++)
    {
        bool found=false;
        for(int j=0;j<nod[i].size();j++)
            if(val[nod[i][j]]==0)
            {
                found=true;
                val[nod[i][j]]=i;
                break;
            }
        if(found)continue;
        for(int j=0;j<nod[i].size();j++)
        {
            found=try_to_change(val[nod[i][j]]);
            if(found)
            {
                val[nod[i][j]]=i;
                break;
            }
        }
    }
    for(int i=1;i<=m;i++)
        if(val[i]!=0)ans++;
    fout<<ans<<"\n";
    for(int i=1;i<=m;i++)
        if(val[i]!=0)
            fout<<val[i]<<" "<<i<<"\n";
    return 0;
}