#include<cstdio>
#include<vector>
#include<cstring>

using namespace std;

vector <int> g[100002];
int nr,used[100002],st[100002],dr[100002],i,n,m,e,x,y;

int cupleaza(int nod)
{
    if(used[nod])
    {
        return 0;
    }
    used[nod]=1;
    for(vector<int> :: iterator i=g[nod].begin();i!=g[nod].end();i++)
    {
        if(!dr[*i])
        {
            dr[*i]=nod;
            st[nod]=*i;
            return 1;
        }
        if(cupleaza(dr[*i]))
        {
            dr[*i]=nod;
            st[nod]=*i;
            return 1;
        }
    }
    return 0;
}

int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    scanf("%d%d%d",&n,&m,&e);
    for(i=1;i<=e;i++)
    {
        scanf("%d%d",&x,&y);
        g[x].push_back(y);
    }
    for(i=1;i<=n;i++)
    {
        if(st[i])
        {
            continue;
        }
        if(cupleaza(i))
        {
            nr++;
        }
        else
        memset(used,0,sizeof(used));
        if(cupleaza(i))
        {
            nr++;
        }
    }
    printf("%d\n",nr);
    for(i=1;i<=n;i++)
    {
        if(st[i])
        {
            printf("%d %d\n",i,st[i]);
        }
    }
    return 0;
}