#include <bits/stdc++.h>
#define MAX 131072
#define INF (1 << 31)
#define MOD 31333
#define fx first
#define fy second

using namespace std;
const int NMAX = 10010;

FILE *IN, *OUT;

int N, M, E, ans;
int leftNodes[NMAX], rightNodes[NMAX];
bool seen[NMAX];

vector <int> edges[NMAX];

int pos, sign;
char f[MAX];

inline void Read(int &nr){
    sign = 0;
    nr = 0;
    while(f[pos] < '0' || f[pos] > '9'){
        if(f[pos] == '-') sign = 1;
        pos++;
        if(pos == MAX)
            fread(f, MAX, 1, IN), pos = 0;
    }
    while(f[pos] >= '0' && f[pos] <= '9'){
        nr = 10 * nr + f[pos++] - '0';
        if(pos == MAX)
            fread(f, MAX, 1, IN), pos = 0;
    }
    if(sign) nr =- nr;
}

void read(){
    Read(N); Read(M); Read(E);
    int a, b;
    for(int i = 1; i <= E; i++){
        Read(a); Read(b);
        edges[a].push_back(b);
    }
}

bool dfs(int node){
    if(seen[node]) return false;
    seen[node] = true;
    for(auto it : edges[node])
        if(!rightNodes[it]){
            rightNodes[it] = node;
            leftNodes[node] = it;
            return true;
        }
    for(auto it : edges[node])
        if(dfs(rightNodes[it])){
            rightNodes[it] = node;
            leftNodes[node] = it;
            return true;
        }
    return false;
}

int main(){

    IN = fopen("cuplaj.in", "r");
    OUT = fopen("cuplaj.out", "w");

    read();

    bool retry = 1;
    while(retry){
        retry = 0;
        for(int i = 1; i <= N; i++)
            seen[i] = false;
        for(int i = 1; i <= N; i++)
            retry |= dfs(i);
    }
    for(int i = 1; i <= N; i++)
        if(rightNodes[i]) ans++;

    fprintf(OUT, "%d\n", ans);
    for(int i = 1; i <= M; i++)
        if(rightNodes[i])
            fprintf(OUT, "%d %d\n", rightNodes[i], i);

    return 0;
}