#include <bits/stdc++.h>
#include <bitset>
#define pb push_back
#define ppb pop_back
#define pf push_front
#define ppf pop_front
#define ll long long
#define sz size()

using namespace std;
/*const long long mod = 998244353;
long long fct[200005],invfct[200005],inv[200005];
long long put2[200005];
long long lgput (long long a, long long exp)
{
    long long rz=1;
    while(exp)
        if(exp&1)
            exp^=1,rz=rz*1LL*a%mod;
        else
            exp>>=1,a=a*1LL*a%mod;
    return rz;
}
long long cmb (long long n, long long k)
{
    if(n<k || k<0 || n<0)
        return 0;
    return fct[n]*1LL*invfct[k]%mod*1LL*invfct[n-k]%mod;
}
void init ()
{
    inv[1]=fct[0]=fct[1]=invfct[0]=invfct[1]=put2[0]=1,put2[1]=2;
    for(long long i=2;i<=200000;++i)
        put2[i]=put2[i-1]*2LL%mod,inv[i]=(mod-mod/i)*1LL*inv[mod%i]%mod,fct[i]=i*1LL*fct[i-1]%mod,invfct[i]=inv[i]*1LL*invfct[i-1]%mod;
}
long long v[200005];*/
//long long
const int inf=1<<30;
//bool viz[10005];
vector<int> v[10005];
int match1[10005],match2[10005];
bitset<10005> viz;
int match(int x1)
{
    if(viz[x1])
       return 0;
    viz[x1]=1;
    for(auto x2:v[x1])
    {
        if(match2[x2]==0 || match(match2[x2])!=0)
        {
            match1[x1]=x2,match2[x2]=x1;
            return x2;
        }
    }
    return 0;
}
void solve()
{
    ifstream cin("cuplaj.in");
    ofstream cout("cuplaj.out");
    int n,m,k;
    bool ok;
    cin>>n>>m>>k;
    for(int i=1;i<=k;i++)
    {
        int a,b;
        cin>>a>>b;
        v[a].pb(b);
    }
    do
    {
        ok=0;
        viz.reset();
        for(int i=1;i<=n;i++)
        {
            if(!match1[i])
            {
                match1[i]=match(i);
                if(match1[i])
                   ok=1;
            }
        }
    }
    while(ok);
    int ans=0;
    for(int i=1;i<=n;i++)
    {
        if(match1[i])
           ans++;
    }
    cout<<ans<<"\n";
    for(int i=1;i<=n;i++)
    {
        if(match1[i])
           cout<<i<<" "<<match1[i]<<"\n";
    }
}
int main()
{
    solve();
    return 0;
}