#include <bits/stdc++.h>
using namespace std;
int x,y,n,m,e,i,st[10010],dr[10010],ans,ok=1;
vector<int>g[10010];
bool ap[10010];
int cuplaj(int node)
{
    if(ap[node])return 0;
    ap[node]=true;
    for(auto &it:g[node])
        if(!st[it])
        {
            st[it]=node;
            dr[node]=it;
            return 1;
        }
    for(auto &it:g[node])
        if(cuplaj(st[it])!=0)
        {
            st[it]=node;
            dr[node]=it;
            return 1;
        }
    return 0;
}
int main()
{
    ifstream cin ("cuplaj.in");
    ofstream cout ("cuplaj.out");
    cin>>n>>m>>e;
    for(i=1; i<=e; ++i)
    {
        cin>>x>>y;
        g[x].push_back(y);
    }
    while(ok)
    {
        ok=0;
        memset(ap,0,sizeof(ap));
        for(i=1; i<=n; ++i)
            if(!dr[i])ok|=cuplaj(i);
    }
    for(i=1; i<=n; ++i)
        if(dr[i])++ans;
    cout<<ans<<'\n';
    for(i=1; i<=n; ++i)
        if(dr[i])cout<<i<<" "<<dr[i]<<'\n';
    return 0;
}