#include <bits/stdc++.h>
///disjoint
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int i,j,n,m,f[100010],fro[100010],to[100010],e,x,y;
vector <int> v[100010];

bool cup(int k)
{
    if(f[k])
        return false;
    f[k]=1;
    for(auto it : v[k])
    {
        if(fro[it]==0 || cup(fro[it]))
        {
            to[k]=it;
            fro[it]=k;
            return true;
        }
    }
    return false;
}
int main()
{
    cin.tie(0);
    cout.tie(0);
    fin>>n>>m>>e;
    for(i=1; i<=e; i++)
    {
        fin>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    bool cha=true;
    while(cha)
    {
        cha=0;
        memset(f,0,sizeof(f));
        for(i=1; i<=n; i++)
            if(to[i]==0)
                cha |= cup(i);
    }
    vector <pair<int, int>> ras;
    for(i=1; i<=m; i++)
        if(fro[i])
            ras.push_back({fro[i],i});
    sort(ras.begin(),ras.end());
    fout<<ras.size()<<'\n';
    for(auto it : ras)
        fout<<it.first<<" "<<it.second<<'\n';
    return 0;
}