#include <bits/stdc++.h>
	
#define ll long long
	
 	
using namespace std;
	
ifstream in("cuplaj.in");
	
ofstream out("cuplaj.out");
	
 	
const int NMAX = 10005;
		
vector<int> g[2 * NMAX];
int dist[2 * NMAX], match[2 * NMAX], n, m;
	

bool dfs(int u) {	
    for(auto v : g[u]) {
        int u2 = match[v];
        if(u2 == 0) {
            match[u] = v;
            match[v] = u;
            return 1;
        } else if(dist[u2] == dist[u] + 1) {
            bool state = dfs(u2);
            if(state == 1) {
                match[u] = v;
                match[v] = u;
                return 1;
            }
        }
    }
    return 0;
}
	
void bfs() {
    queue<int> q;
    for(int i = 1; i <= n; i ++) {
        if(match[i] == 0) {
            q.push(i);
            dist[i] = 0;
        } else
            dist[i] = -1;
    }

    while(q.size()) {	
        int u = q.front();
        q.pop();
        for(auto v : g[u]) {
            int u2 = match[v];
            if(u2 && dist[u2] == -1) {
                dist[u2] = dist[u] + 1;
                q.push(u2);
            }
        }
    }
}
	
int hopcroftkarp() {
    int ans = 0;
    bool found = 1;
    while(found) {
        found = 0;
        bfs();
        for(int i = 1; i <= n; i ++) {
            if(dist[i] == 0 && dfs(i) == 1) {
                found = 1;
                ans ++;
            }
        }
    }
	
    return ans;
}
	
int main() {
    int e;
    in >> n >> m >> e;
    for(int i = 1; i <= e; i ++) {
        int x, y;
        in >> x >> y;
        y += n;
        g[x].push_back(y);
        g[y].push_back(x);
    }
	
    out << hopcroftkarp() << "\n";
    for(int i = 1; i <= n; i ++)
        if(match[i])
            out << i << " " << match[i] - n << "\n";
    return 0;
}