#include <bits/stdc++.h>
using namespace std;
fstream f("cuplaj.in");
ofstream g("cuplaj.out");
const int NMAX=10005,INF=0x3F3F3F3F;
int n,m,e,x,y,c,maxx,no_of_pictures;
bool SCALING=0;///you can choose between having scaling and not having scaling
///it is better without scaling on edges with lower costs, but on high cost edges, scaling helps a lot
struct edge
{
    int node,flow,capacity,index;
};
vector<int>level,skip;
vector<edge>graph[2*NMAX];///because we will double the nodes
void add_edge(int x,int y)
{
    graph[x].push_back({y,0,1,0});///to node,flow,capacity,index
    graph[y].push_back({x,0,0,0});///reverse edge:to node,flow,capacity,index
    graph[x].back().index=graph[y].size()-1;///index from adjacency list of y
    graph[y].back().index=graph[x].size()-1;///index from adjacency list of x
}
void read_and_create_graph()
{
    maxx=c=1;///because we do maximum matching in a bipartite graph
    f>>n>>m>>e;
    for(int i=1; i<=e; i++)
    {
        f>>x>>y;
        add_edge(x,y+n);///we add an edge from the node on the left to the node on the right
    }
    for(int i=1; i<=n; i++) ///we add the edges from the source
        add_edge(2*n+1,i);
    for(int i=1; i<=m; i++) ///we add the edges to the terminal
        add_edge(i+n,2*n+2);
}
bool bfs(int s,int t,int limit)
{
    level.assign(2*n+3,-1);///because we do maximum matching in a bipartite graph and we have 2*n+2 nodes
    level[s]=0;
    queue<int>q;
    q.push(s);
    while(!q.empty())
    {
        int node=q.front();
        q.pop();
        for(edge& link:graph[node])
            if(link.capacity-link.flow>0 && level[link.node]==-1 && (!SCALING || link.capacity-link.flow>=limit))///if I can still push flow and the next node is not visited
            {
                level[link.node]=level[node]+1;
                q.push(link.node);
            }
    }
    return level[t]!=-1;///if t was visited it will return 1,otherwise 0
}
int dfs(int node,int t,int cur_flow)
{
    if(node==t)
        return cur_flow;
    for(; skip[node]<(int)graph[node].size(); skip[node]++)///we start from the pointer we have for this node
    {
        int next=graph[node][skip[node]].node;
        edge& link=graph[node][skip[node]];///for simplicity
        if(link.capacity-link.flow>0 && level[node]+1==level[next])///if I can still push flow and the node is not visited and we only go forward
        {
            int bottleNeck=dfs(next,t,min(cur_flow,link.capacity-link.flow));
            if(bottleNeck>0)
            {
                link.flow+=bottleNeck;///update on the normal edge
                graph[next][link.index].flow-=bottleNeck;///update on the reverse edge
                return bottleNeck;
            }
        }
    }
    return 0;
}
int maxflow(int s,int t)
{
    int max_flow=0;
    skip.resize(2*n+3);///because we do maximum matching in a bipartite graph and we have 2*n+2 nodes
    for(int limit=SCALING ? (1<<(int(log2(maxx)))) : 1; limit>0; limit=limit/2)
        while(bfs(s,t,limit))
        {
            fill(skip.begin(),skip.end(),0);///for pruning dead ends
            for(int new_flow=dfs(s,t,INF); new_flow!=0; new_flow=dfs(s,t,INF))///as long as we can find a new path we increase the max_flow
                max_flow+=new_flow;
        }
    return max_flow;
}
void write()
{
    g<<maxflow(2*n+1,2*n+2)<<'\n';///the maximum flow is equal to the number of matchings in our graph
    for(int i=1; i<=n; i++)
        for(int j=0; j<graph[i].size()-1; j++) ///because we don't want to take the source into consideration
            if(graph[i][j].flow==1)
                g<<i<<' '<<graph[i][j].node-n<<'\n';
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    read_and_create_graph();
    write();
    return 0;
}