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


#define INF 0x3f3f3f3f
char *p1, *p2, buf[1000000];
#define gc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1000000,stdin),p1==p2)?EOF:*p1++)
inline int read() {int x=0;char c=gc();while(!isdigit(c))c=gc();while(isdigit(c))x=x*10+c-'0',c=gc();return x;}
#define pc(c) putchar(c)
void write(int x) {if(x>9)write(x/10);pc('0'+x%10);}

int head[200010], cur[200010], tot = 1;
int dis[200010];
struct Edge {int fr, to, nxt, f, c;} e[800010];
int S, T;

inline void add_edge(int u, int v, int c) {
    e[++tot] = {u, v, head[u], 0, c};
    head[u] = tot;
    e[++tot] = {v, u, head[v], 0, 0};
    head[v] = tot;
}

inline bool bfs() {
    memset(dis, 0, sizeof(dis));
    queue<int> Q; Q.push(S); dis[S] = 1;
    while (!Q.empty()) {
        int u = Q.front(); Q.pop();
        for (int i = head[u]; i; i = e[i].nxt) {
            int v = e[i].to;
            if (e[i].c - e[i].f == 0) continue;
            if (!dis[v]) dis[v] = dis[u] + 1, Q.push(v);
        }
    }
    return dis[T] != 0;
}

int dfs(int u, int f) {
    if (u == T || !f) return f;
    int ret = 0;
    for (int &i = cur[u]; i && ret < f; i = e[i].nxt) {
        int v = e[i].to, d;
        if (dis[u] + 1 == dis[v] && (d = dfs(v, min(e[i].c - e[i].f, f - ret)))) {
            ret += d;
            e[i].f += d;
            e[i ^ 1].f -= d;
        }
    }
    return ret;
}

inline int dinic() {
    int f = 0;
    while (bfs()) {
        memcpy(cur, head, sizeof(cur));
        f += dfs(S, INF);
    }
    return f;
}

int l, r, m;

int main() {
    l = read(), r = read(), m = read();
    for (int i = 1; i <= m; i++) {
        int a = read() + 1, b = read() + 1;
        add_edge(a, l + b, 1);
    }
    S = l + r + 1, T = l + r + 2;
    for (int i = 1; i <= l; i++) {
        add_edge(S, i, 1);
    }
    for (int i = 1; i <= r; i++) {
        add_edge(l + i, T, 1);
    }
    write(dinic()); pc('\n');
    for (int i = 2; i <= tot; i++) {
        if (e[i].fr == S || e[i].to == T) continue;
        if (e[i].f == 1) {
            write(e[i].fr - 1), pc(' ');
            write(e[i].to - 1 - l), pc('\n');
        }
    }
    return 0;
}