#include<fstream>
#include<cstring>
#include<vector>

#define MAXN 10005

using namespace std;
vector<int> G[MAXN];
int u[MAXN], l[MAXN], r[MAXN];


bool pairup(int x){
    if(u[x]) return false;
    u[x] = true;
    for(vector<int>::iterator it=G[x].begin(); it!=G[x].end(); ++it)
        if(!r[*it]){
            r[*it] = x;
            l[x] =*it;
            return true;
        }

    for(vector<int>::iterator it=G[x].begin(); it!=G[x].end(); ++it)
        if(pairup(r[*it])){
            r[*it] = x;
            l[x] = *it;
            return true;
        }

    return false;
}

int main(){
    int n, m, edges, i, j, x, y, sum;
    freopen("cuplaj.in", "rt", stdin);
    freopen("cuplaj.out", "wt", stdout);

    scanf("%d %d %d", &n, &m, &edges);
    for(i=0; i<edges; i++){
        scanf("%d %d",&x, &y);
        G[x].push_back(y);
    }

    for(bool change=true; change; ){
        change = false;
        memset(u, 0, sizeof(u));
        for(i=1; i<=n; i++)
            if(!l[i]) change= change | pairup(i);
    }

    for(sum=0, i=1; i<=n; i++)
        sum+=(l[i]!=0);
    printf("%d\n", sum);
    for(i=1; i<=n; i++)
        if(l[i])printf("%d %d\n", i, l[i]);

    fclose(stdin);
    fclose(stdout);
    return 0;
}