#include<cstdio>
#include<vector>
#include<cstring>
#define nx 10007
using namespace std;
int n,m,nr,i,x,y,k,s[nx],d[nx],viz[nx];
vector<int>v[nx];

void citire()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    scanf("%d %d %d",&n,&m,&nr);

    for(i=1;i<=nr;i++)
    {
        scanf("%d %d",&x,&y);
        v[x].push_back(y);
    }
}

int re(int x)
{
    int j;
    if(viz[x])return 0;
    viz[x]=1;

    for(j=0;j<v[x].size();j++)
    if(!d[v[x][j]])
    {
        s[x]=v[x][j];
        d[v[x][j]]=x;
        return 1;
    }

    for(j=0;j<v[x].size();j++)
    if(re(d[v[x][j]]))
    {
        s[x]=v[x][j];
        d[v[x][j]]=x;
        return 1;
    }
    return 0;
}

void afisare()
{
    for(i=1;i<=n;i++)if(s[i])k++;
    printf("%d\n",k);
    for(i=1;i<=n;i++)if(s[i])printf("%d %d\n",i,s[i]);
}

int main()
{
    citire();

    k=1;
    while(k)
    {
        k=0;
        memset(viz,0,sizeof(viz));

        for(i=1;i<=n;i++)
           if(!s[i])k+=re(i);
    }

    afisare();
    return 0;
}