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

int n,m,e,nr;
vector < vector <int> > Graf;
int dr[NMAX];
int st[NMAX];
int vizitat[NMAX];

inline void citesc(){

    int x,y;
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    scanf("%d%d%d",&n,&m,&e);
    Graf.resize(2*n+1);
    for(register int i=1;i<=e;++i){
        scanf("%d%d",&x,&y);
        Graf[x].push_back(y);
    }
}

int Hopcroft_Karp(int nod){

   if(vizitat[nod]) return 0;
   vizitat[nod] = 1;
    for(vector < int >::iterator it = Graf[nod].begin();it!=Graf[nod].end();++it)
        if(!dr[*it] || Hopcroft_Karp(dr[*it])){
            st[nod] = *it;
            dr[*it] = nod;
            return 1;
        }
return 0;
}

inline void solve(){

    int ok=1;
    while(ok){
        ok = 0;
    for(register int i=1;i<=n;++i)
        if(!st[i])
        if(Hopcroft_Karp(i)) ok=1,++nr;

            memset(vizitat,0,sizeof(vizitat));

}
    printf("%d\n",nr);
    for(register int i=1;i<=n;++i)
        if(st[i])
            printf("%d %d\n",i,st[i]);
}

int main(){

    citesc();
    solve();

return 0;
}