#include<bits/stdc++.h>
#define ll long long
const int inf=1e9;
using namespace std;
int l[20005],r[20005],dist[20005];
vector<int>g[20005];
int n,m;
queue<int>q;
int bfs()
{
    int i;
    for(i=1;i<=n;i++)
        if (l[i]==n+m+1)
            dist[i]=0,q.push(i);
        else
            dist[i]=inf;
    dist[n+m+1]=inf;
    while(!q.empty()){
        int nod=q.front();
        q.pop();
        if (dist[nod]<dist[n+m+1])
            for(auto it:g[nod])
                if (dist[r[it]]==inf){
                    dist[r[it]]=dist[nod]+1;
                    q.push(r[it]);
            }
    }
    return dist[n+m+1]!=inf;
}
int dfs(int nod)
{
    if (nod!=n+m+1){
        for(auto it:g[nod])
            if (dist[r[it]]==dist[nod]+1)
                if (dfs(r[it])){
                    l[nod]=it;
                    r[it]=nod;
                    return 1;
                }
        dist[nod]=inf;
        return 0;
    }
    return 1;
}
int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    int e;
    int i;
    scanf("%d%d%d",&n,&m,&e);
    for(i=1;i<=e;i++){
        int a,b;
        scanf("%d%d",&a,&b);
        g[a].push_back(n+b);
        g[n+b].push_back(a);
    }
    for(i=1;i<=n;i++)
        l[i]=n+m+1;
    for(i=n+1;i<=n+m;i++)
        r[i]=n+m+1;
    int cupl=0;
    while(bfs()){
        for(i=1;i<=n;i++)
            if (l[i]==n+m+1)
                if (dfs(i))
                    cupl++;
    }
    printf("%d\n",cupl);
    for(i=1;i<=n;i++)
        if (l[i]!=n+m+1)
            printf("%d %d\n",i,l[i]-n);
return 0;
}