#include<cstdio>
#include<algorithm>
#define fo(i,x,y) for(int i = x;i <= y;++i)
#define fd(i,x,y) for(int i = x;i >= y;--i)
#define _is 1048576 * 10
#define gc() ib[++bi]
using namespace std;
char ib[_is];int bi = -1;
int rd()
{
	int x = 0;char ch = gc();
	while(ch < 48 || ch > 57) ch = gc();
	while(ch >= 48 && ch <= 57) x = x * 10 + ch - 48,ch = gc();
	return x;
}
int m,l,r,S,T,x,y;
int lst[200010],L[200010],d[200010],e[800010][2],tot = 1,Q[200010];
bool vs[200010],f[800010];
void add(int x,int y)
{
	e[++tot][0] = y,f[tot] = 1,e[tot][1] = lst[x],lst[x] = tot;
	e[++tot][0] = x,f[tot] = 0,e[tot][1] = lst[y],lst[y] = tot;
}
bool bfs()
{
	fo(i,0,T) vs[i] = 0;
	int st = 0,en = 1;Q[1] = S,vs[S] = 1;
	while(st < en)
	{
		int x = Q[++st];
		for(int i = lst[x];i;i = e[i][1])
		{
			int v = e[i][0];
			if(vs[v] == 0 && f[i]) vs[v] = 1,d[v] = d[x] + 1,Q[++en] = v;
		}
	}
	return vs[T];
}
#define min(x,y) (x < y ? x : y)
int dfs(int x,int fl)
{
	if(x == T || fl == 0) return fl;
	int F = 0;
	for(int &i = L[x];i;i = e[i][1])
	{
		int v = e[i][0];
		if((d[x] + 1) ^ d[v]) continue;
		int now = dfs(v,min(fl,f[i]));
		if(now <= 0) continue;
		f[i] -= now,f[i ^ 1] += now,F += now,fl -= now;
		if(fl == 0) break;
	}
	return F;
}
int main()
{
	fread(ib,1,_is,stdin);
	l = rd(),r = rd(),m = rd(),S = 0,T = l + r + 1;
	fo(i,1,l) add(S,i),add(i + l,T);
    fo(i,1,m) x = rd() + 1,y = rd() + 1,add(x,y + l);
	int ans = 0;
	while(bfs())
	{
		fo(i,0,T) L[i] = lst[i];
		ans += dfs(0,l);
	}
	printf("%d\n",ans);
    fo(i,1,l) for(int j = lst[i];j;j = e[j][1]) if(e[j][0] > l && f[j] == 0) {printf("%d %d\n",i - 1,e[j][0] - l - 1);break;}
}