#include <bits/stdc++.h>
#define ll long long
using namespace std;

namespace IO {
	#if ONLINE_JUDGE
	#define getc() (IS == IT && (IT = (IS = ibuf) + fread(ibuf, 1, IL, stdin), IS == IT) ? EOF : *IS++)
	#else
	#define getc() getchar()
	#endif
	const int IL = 1 << 21, OL = 1 << 21;
	int olen = 0;
	char ibuf[IL], *IS = ibuf, *IT = ibuf, obuf[OL];
	inline int read() {
		register char ch = getc(); register int x = 0, f = 1;
		while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getc(); }
		while(isdigit(ch)) x = x * 10 + ch - 48, ch = getc();
		return x * f;
	}
	inline double readdb() {
		register char ch = getc(); register double x = 0, f = 1;
		while(!isdigit(ch)) { if(ch == '-') f = -1; ch = getc(); }
		while(isdigit(ch)) x = x * 10 + ch - 48, ch = getc();
		if(ch == '.') {
			register double b = 0.1;
			ch = getc();
			while(isdigit(ch)) x += (ch - 48) * b, b *= 0.1, ch = getc();
		}
		return x * f;
	}
	inline int readstr(char *s) {
		register char ch = getc(); register int len = 0;
		while(!isalpha(ch)) ch = getc();
		while(isalpha(ch)) s[++len] = ch, ch = getc();
		return len;
	}
	inline void flush() { fwrite(obuf, 1, olen, stdout); olen = 0; }
	inline void putc(register char ch) { obuf[olen++] = ch; }
	template<class T>
	inline void write(register T x) {
		if(x < 0) obuf[olen++] = '-', x = -x;
		if(x > 9) write(x / 10);
		obuf[olen++] = x % 10 + 48;
	}
} using namespace IO;
const int N = 2e5 + 10, M = 2e5 + 10;
int S, T;
struct edge {
	int to, w, nxt;
} e[M << 1];
int head[N], ecnt = 1;
void addedge(int u, int v, int w) {
	e[++ecnt] = {v, w, head[u]};
	head[u] = ecnt;
	e[++ecnt] = {u, 0, head[v]};
	head[v] = ecnt;
}
int dep[N], now[N];
bool bfs() {
	memset(dep, 0, sizeof(dep));
	queue<int> q;
	q.push(S);
	dep[S] = 1;
	while(!q.empty()) {
		int u = q.front();
		q.pop();
		now[u] = head[u];
		for(int i = head[u], v; i; i = e[i].nxt) {
			v = e[i].to;
			if(e[i].w && !dep[v]) {
				dep[v] = dep[u] + 1;
				q.push(v);
			}
		}
	}
	return dep[T];
}
ll dfs(int u, ll sum) {
	if(u == T) return sum;
	ll res = 0, flow;
	for(int i = now[u], v; i; i = e[i].nxt) {
		now[u] = i;
		v = e[i].to;
		if(dep[v] == dep[u] + 1 && e[i].w) {
			flow = dfs(v, min(sum, 1ll * e[i].w));
			e[i].w -= flow;
			e[i ^ 1].w += flow;
			sum -= flow;
			res += flow;
			if(!sum) break;
		}
	}
	if(!res) dep[u] = 0;
	return res;
}
ll dinic() { ll ans = 0; while(bfs()) ans += dfs(S, 1e18); return ans; }
int main() {
	int L = read(), R = read(), m = read();
	S = L + R + 1, T = L + R + 2;
	for(int i = 1; i <= L; i++)
		addedge(S, i, 1);
	for(int i = 1; i <= R; i++)
		addedge(L + i, T, 1);
	for(int i = 1; i <= m; i++) {
		int u = read() + 1, v = read() + 1;
		addedge(u, L + v, 1);
	}
	printf("%d\n", dinic());
	for(int u = 1; u <= L; u++)
		for(int i = head[u], v; i; i = e[i].nxt) {
			v = e[i].to;
			if(v == S) continue;
			if(!e[i].w) printf("%d %d\n", u - 1, v - L - 1);
		}
	return 0;
}