#include <bits/stdc++.h>
#define _rep(i, x, y) for(int i = x; i <= y; ++i)
#define _req(i, x, y) for(int i = x; i >= y; --i)
#define _rev(i, u) for(int i = head[u]; i; i = e[i].nxt)
#define pb push_back
#define fi first
#define se second
#define mst(f, i) memset(f, i, sizeof f)
using namespace std;
#ifdef ONLINE_JUDGE
#define debug(...) 0
#else
#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#endif
typedef long long ll;
typedef pair<int, int> PII;
namespace fastio{
    char ibuf[50007],*p1 = ibuf, *p2 = ibuf;
    #ifdef ONLINE_JUDGE
    #define get() p1 == p2 && (p2 = (p1 = ibuf) + fread(ibuf, 1, 50007, stdin), p1 == p2) ? EOF : *p1++
    #else
    #define get() getchar()
    #endif
    template<typename T> inline void read(T &t){
        T x = 0, f = 1;
        char c = getchar();
        while(!isdigit(c)){
            if(c == '-') f = -f;
            c = getchar();
        }
        while(isdigit(c)) x = x * 10 + c - '0', c = getchar();
        t = x * f;
    }
    template<typename T, typename ... Args> inline void read(T &t, Args&... args){
        read(t);
        read(args...);
    }
    template<typename T> void write(T t){
        if(t < 0) putchar('-'), t = -t;
        if(t >= 10) write(t / 10);
        putchar(t % 10 + '0');
    }
    template<typename T, typename ... Args> void write(T t, Args... args){
        write(t), putchar(' '), write(args...);
    }
    template<typename T> void writeln(T t){
        write(t);
        puts("");
    }
    template<typename T> void writes(T t){
        write(t), putchar(' ');
    }
    #undef get
};
using namespace fastio;
#define multitest() int T; read(T); _rep(tCase, 1, T)
namespace Calculation{
    const ll mod = 998244353;
    ll ksm(ll p, ll h){ll base = p % mod, res = 1; while(h){if(h & 1ll) res = res * base % mod; base = base * base % mod, h >>= 1ll;} return res;}
    void dec(ll &x, ll y){x = ((x - y) % mod + mod) % mod;}
    void add(ll &x, ll y){x = (x + y) % mod;}
    void mul(ll &x, ll y){x = x * y % mod;}
    ll sub(ll x, ll y){return ((x - y) % mod + mod) % mod;}
    ll pls(ll x, ll y){return ((x + y) % mod + mod) % mod;}
    ll mult(ll x, ll y){return x * y % mod;}
}
using namespace Calculation;
const int N = 1e5 + 5;
const ll inf = 1e18;
int n, s, t;
int ecnt = 1, head[N];
struct edge{
    ll v, w, nxt;
}e[N];
void add(int u, int v, int w){
    e[++ecnt] = edge{v, w, head[u]}, head[u] = ecnt;
    e[++ecnt] = edge{u, 0, head[v]}, head[v] = ecnt;
}
int cur[N], dis[N];
bool bfs(int s, int t){
    mst(dis, 0);
    queue<int> q; q.push(s), dis[s] = 1, cur[s] = head[s];
    while(q.size()){
        int u = q.front(); q.pop();
        _rev(i, u){
            int v = e[i].v;
            if(!dis[v] && e[i].w){
                dis[v] = dis[u] + 1;
                cur[v] = head[v];
                q.push(v);
            }
        }
    }
    return dis[t];
}
ll dfs(int u, ll in){
    if(u == t) return in;
    ll out = 0;
    for(int i = cur[u]; i && in; i = e[i].nxt){
        int v = e[i].v;
        cur[u] = i;
        if(e[i].w && dis[v] == dis[u] + 1){
            ll d = dfs(v, min(in, e[i].w));
            e[i].w -= d, e[i ^ 1].w += d;
            in -= d, out += d;
        }
    }
    if(!out) dis[u] = 0;
    return out;
}
ll Dinic(){
    ll flow = 0;
    while(bfs(s, t)) flow += dfs(s, inf);
    return flow;
}
int L, R, m;
int main(){
    read(L, R, m);
    s = 0, t = L + R + 1;
    _rep(i, 1, m){
        int u, v; read(u, v);
        u++, v++;
        add(u, v + L, 1);
    }
    _rep(i, 1, L) add(s, i, 1); _rep(i, L + 1, L + R) add(i, t, 1);
    writeln(Dinic());
    _rep(i, 1, L){
        int u = i, v = 0;
        _rev(j, i){
            if(e[j ^ 1].w && e[j].v > L){
                v = e[j].v - L;
            }
        }
        if(!v) continue;
        write(u - 1, v - 1), puts("");
    }
    return 0;
}