#include <cstdio>
#include <vector>
#include <cstring>
using namespace std;
#define Max 10001

vector<int>v[Max];
int n,m,st[Max],dr[Max];
bool was[Max];

bool dfs(int x)
{
    int y;
    if(was[x])return 0;
    was[x]=1;
    for(int i=0;i<v[x].size();i++)
    {
        y=v[x][i];
        if(st[y]==0 || dfs(st[y]))
        {
            st[y]=x;
            dr[x]=y;
            return 1;
        }
    }
    return 0;
}

void cuplaj()
{
    int nr=0, next=1;
    while(next)
    {
        next=0;
        memset(was,0,sizeof(was));
        for(int i=1;i<=n;i++)
        if(dr[i]==0 && dfs(i))
        {
            next=1;
            nr++;
        }
    }
    printf("%d\n",nr);
    for(int i=1;i<=n;i++)
    if(dr[i])printf("%d %d\n",i,dr[i]);
}

int main()
{
    int e,x,y;
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
        scanf("%d %d %d",&n,&m,&e);
        while(e--)
        {
            scanf("%d %d",&x,&y);
            v[x].push_back(y);
        }
    cuplaj();
    return 0;
}