#include <stdio.h>
#include <string.h>
#define MAXN 10000
#define MAXE 100000
int val[MAXE+1], next[MAXE+1], lista[MAXN+1], fata[MAXN+1], bajatu[MAXN+1], viz[MAXN+1], k;
inline void adauga(int x, int y){
    val[++k]=y;
    next[k]=lista[x];
    lista[x]=k;
}
int gasim(int x){
    if(viz[x]){
        return 0;
    }
    viz[x]=1;
    int p=lista[x];
    while(p){
        if(bajatu[val[p]]==0){
            bajatu[val[p]]=x;
            fata[x]=val[p];
            return 1;
        }
        p=next[p];
    }
    p=lista[x];
    while(p){
        if(gasim(bajatu[val[p]])){
            bajatu[val[p]]=x;
            fata[x]=val[p];
            return 1;
        }
        p=next[p];
    }
    return 0;
}
int main(){
    int n, m, e, x, y, f, i, ans;
    FILE *fin, *fout;
    fin=fopen("cuplaj.in", "r");
    fout=fopen("cuplaj.out", "w");
    fscanf(fin, "%d%d%d", &n, &m, &e);
    for(i=0; i<e; i++){
        fscanf(fin, "%d%d", &x, &y);
        adauga(x, y);
    }
    f=1;
    while(f){
        f=0;
        memset(viz, 0, sizeof viz);
        for(i=1; i<=n; i++){
            if(fata[i]==0){
                if(gasim(i)){
                    f=1;
                }
            }
        }
    }
    ans=0;
    for(i=1; i<=n; i++){
        if(fata[i]){
            ans++;
        }
    }
    fprintf(fout, "%d\n", ans);
    for(i=1; i<=n; i++){
        if(fata[i]){
            fprintf(fout, "%d %d\n", i, fata[i]);
        }
    }
    fclose(fin);
    fclose(fout);
    return 0;
}