#include<bits/stdc++.h>
using namespace std;
int d[1001000];
int to[1001000],nxt[1001000],cn=1,hd[1010000],S,T;
int flow[1000100];
void ad(int u,int v,int w){
    to[++cn]=v,flow[cn]=w,nxt[cn]=hd[u],hd[u]=cn;
    to[++cn]=u,flow[cn]=0,nxt[cn]=hd[v],hd[v]=cn;
}
const int I=1e9;
int cur[1010000];
bool bfs(){
    for(int i=1;i<=T;i++)d[i]=0,cur[i]=hd[i];
    queue<int>q;q.push(S),d[S]=1;
    while(!q.empty()){
        int u=q.front();q.pop();
        for(int i=hd[u];i;i=nxt[i])if(flow[i]&&!d[to[i]])
            d[to[i]]=d[u]+1,q.push(to[i]);
    }
    return d[T]>0;
}
int dfs(int u,int in){
    if(u==T)return in;int out=0;
    for(int &i=cur[u];i&&in;i=nxt[i])if(flow[i]&&d[to[i]]==d[u]+1){
        int e=dfs(to[i],min(in,flow[i]));
        flow[i]-=e,flow[i^1]+=e;
        in-=e,out+=e;
    }
    if(!out)d[u]=0;
    return out;
}
int n1,n2,m;
int main(){
    scanf("%d%d%d",&n1,&n2,&m);S=n1+n2+1,T=S+1;
    for(int i=1,u,v;i<=m;i++)
        scanf("%d%d",&u,&v),u++,v++,ad(u,v+n1,1);
    for(int i=1;i<=n1;i++)ad(S,i,1);
    for(int i=1;i<=n2;i++)ad(i+n1,T,1);
    int ans=0;
    while(bfs())ans+=dfs(S,I);printf("%d\n",ans);
    for(int i=1;i<=n1;i++)
        for(int j=hd[i];j;j=nxt[j])if(to[j]>n1&&to[j]<S&&!flow[j])
        printf("%d %d\n",i-1,to[j]-1-n1);
    return 0;
}