#include<iostream>
#include<climits>
#include<queue>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<cstring>
#include<array>
#define endl '\n'
using namespace std;
using ll = long long;
using pi2 = array<int,2>;
using pi3 = array<int,3>;

const int N=2e5+500,M=4e5+50;
struct Edge{
    int u,v,w,nxt;
} edges[M*2];
int head[N],ecnt;
void add_edge_(int u,int v,int w){
    edges[++ecnt]={u,v,w,head[u]};
    head[u]=ecnt;
}
void add_edge(int u,int v,int w){
    add_edge_(u,v,w),add_edge_(v,u,0);
}
int cpy[N],dis[N];
bool bfs(int s,int t){
    memcpy(cpy,head,sizeof(cpy)),memset(dis,0x3f,sizeof(dis));
    queue<int> q;
    q.push(s),dis[s]=0;
    while(q.size()){
        int u=q.front();
        q.pop();
        for(int i=head[u];i;i=edges[i].nxt){
            if(edges[i].w&&dis[edges[i].v]>dis[edges[i].u]+1){
                dis[edges[i].v]=dis[edges[i].u]+1;
                q.push(edges[i].v);
            }
        }
    }
    return dis[t]<0x3f3f3f3f;
}
ll dfs(int u,int t,int minf){
    if(u==t||!minf)return minf;
    ll f,flow=0;
    for(int &i=cpy[u];i;i=edges[i].nxt){
        if(edges[i].w&&dis[edges[i].v]==dis[edges[i].u]+1){
            if(f=dfs(edges[i].v,t,min(edges[i].w,minf))){
                flow+=f,minf-=f,edges[i].w-=f,edges[((i-1)^1)+1].w+=f;
                if(!minf)return flow;
            }else{
                dis[edges[i].v]=-1;
            }
        }
    }
    return flow;
}
ll dinic(int s,int t){
    ll flow=0;
    while(bfs(s,t))
        flow+=dfs(s,t,INT_MAX);
    return flow;
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n1,n2,m,s,t;
    cin>>n1>>n2>>m;
    s=n1+n2+1,t=s+1;
    for(int i=1;i<=m;i++){
        int u,v;
        cin>>u>>v;
        u++,v++;
        add_edge(u,v+n1,1);
    }
    for(int i=1;i<=n1;i++)add_edge(s,i,1);
    for(int i=1;i<=n2;i++)add_edge(i+n1,t,1);
    int f=dinic(s,t);
    cout<<f<<endl;
    for(int i=1;i<=ecnt;i++){
        if(edges[i].u<=n1&&edges[i].v<=n1+n2&&edges[i].w==0){
            cout<<edges[i].u-1<<" "<<edges[i].v-n1-1<<endl;
        }
    }
    return 0;
}