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

using namespace std;

vector<int> g[10002];
int st[10002],nr,x,y,dr[10002],i,e,ok,n,m;
bool fol[10002];

int cupleaza(int nod)
{
    if(fol[nod])
    {
        return 0;
    }
    fol[nod]=true;
    for(vector<int>::iterator it=g[nod].begin();it!=g[nod].end();it++)
    {
        if(!dr[*it]||cupleaza(dr[*it]))
        {
            dr[*it]=nod;
            st[nod]=*it;
            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);
    }
    ok=1;
    while(ok)
    {
        memset(fol,false,sizeof(fol));
        ok=0;
        for(i=1;i<=n;i++)
        {
            if(!st[i])
            {
                ok+=cupleaza(i);
            }
        }
    }
    for(i=1;i<=n;i++)
    {
        if(st[i])
        {
            ++nr;
        }
    }
    printf("%d\n",nr);
    for(i=1;i<=n;i++)
    {
        if(st[i])
        {
            printf("%d %d\n",i,st[i]);
        }
    }
    return 0;
}