#include<iostream>
#include<cstdio>
#include<fstream>
#include<queue>
#include<algorithm>
#include<cstring>
#include<map>
#define fi first
#define se second
#define maxn 100005
#define maxm 300005
#define fopen(x, y) freopen(x".in", "r", stdin); freopen(y".out", "w", stdout);
#define int long long
#ifdef int
#define inf 0x3f3f3f3f3f3f3f3fll
#else
#define inf 0x3f3f3f3f
#endif

using namespace std;

struct Graph {
	struct Edge {
		int u, v, w, s, next;
	} e[maxm];
	struct Info {
		int fl, cs;
		Info(int _fl = 0, int _cs = 0) : fl(_fl), cs(_cs) {}
		Info operator+(Info b) const {
			return Info(fl + b.fl, cs + b.cs);
		}
		Info& operator+=(Info b) { return (*this = *this + b); }
	};
	int h[maxn], now[maxn], dis[maxn], vis[maxn], n, en, s, t;
	void clear() {
		memset(h, 0xff, sizeof(h));
		memset(now, 0xff, sizeof(now));
		n = en = s = t = 0;
	}
	Graph() {
		clear();
	}
	void add(int u, int v, int w, int s, int _s = 0) {
		e[en] = (Edge){ u, v, w, s, h[u] }; h[u] = en++;
		e[en] = (Edge){ v, u, -w, _s, h[v] }; h[v] = en++;
		n = max(n, max(u, v));
	}
	bool spfa() {
		queue<int> q;
		for(int i = 0; i <= n; i++) {
			dis[i] = inf; vis[i] = 0;
		}
		dis[s] = 0; q.push(s); now[s] = h[s];
		while(!q.empty()) {
			int r = q.front(); q.pop();
			for(int j = h[r]; ~j; j = e[j].next) {
				int v = e[j].v;
				if(dis[v] > dis[r] + e[j].w && e[j].s) {
					dis[v] = dis[r] + e[j].w;
					q.push(v);
					now[v] = h[v];
				}
			}
		}
		return dis[t] < inf;
	}
	Info dinic(int r, int lft = inf) {
		if(r == t) return Info(lft, 0);
		vis[r] = 1;
		Info sum, k;
		for(int j = h[r]; ~j; j = e[j].next) {
			int v = e[j].v;
			if(dis[v] != dis[r] + e[j].w || vis[v] || !e[j].s) continue;
			k = dinic(v, min(lft, e[j].s));
			if(k.fl == 0) dis[v] = inf;
			sum += k; lft -= k.fl;
			e[j].s -= k.fl; e[j ^ 1].s += k.fl;
			sum.cs += e[j].w * k.fl;
			if(!lft) break;
		}
		return sum;
	}
	Info stream(int _s, int _t) {
		s = _s, t = _t;
		Info res;
		while(spfa()) {
			res += dinic(_s);
		}
		return res;
	}
	Info stream2(int _s, int _t) {
		s = _s, t = _t;
		Info res;
		while(spfa() && dis[t] < 0) {
			res += dinic(_s);
		}
		return res;
	}
} f, g; 

int n1, n2, n, m, deg[maxn], u[maxm], v[maxm], a[maxn], b[maxn], fa[maxn], vis[maxn], id[maxn], od[maxn];

int x, y;

queue<pair<int, int> > tdl;

map<int, queue<int> > q[3005];

bool dfs(int r) {
//	cout << "dfs " << r << '\n';
	vis[r] = 2;
	for(int j = f.h[r]; ~j; j = f.e[j].next) {
		if(!f.e[j].s || f.e[j].w < 0) continue;
		int v = f.e[j].v; 
		if(!vis[v]) {
			fa[v] = r;
			if(dfs(v)) {
				if(y) {
					f.e[j].s = 0;
					tdl.push(make_pair(r, v));
				}
				if(r == x) y = 0;
				vis[r] = 1;
				return true;
			}
		}
		else if(vis[v] == 2) {
//			cout << r << " lnk " << v << '\n';
			x = v, y = 1; 
			f.e[j].s = 0;
			tdl.push(make_pair(r, v));
			vis[r] = 1;
			return true;
		}
	}
	vis[r] = 1;
	return false;
}
bool dfs2(int r) {
	if(od[r] == 0) return true;
	vis[r] = 1;
	for(int j = f.h[r]; ~j; j = f.e[j].next) {
		if(!f.e[j].s || f.e[j].w < 0) continue;
		int v = f.e[j].v;
		if(!vis[v]) {
			fa[v] = r;
			if(dfs2(v)) {
				f.e[j].s = 0;
				tdl.push(make_pair(r, v));
				return true;
			}
		}
	}
	return false;
}

void work() {
	cin >> n1 >> n2 >> m;
	n = n1 + n2;
//	for(int i = 1; i <= n; i++) cin >> b[i];
	for(int i = 1; i <= m; i++) {
		cin >> u[i] >> v[i];
		q[u[i]][v[i]].push(i);
		deg[u[i]] ^= 1, deg[v[i]] ^= 1;
	}
//	for(int i = 1; i <= n; i++) deg[i] = b[i];
	for(int i = 1; i <= m; i++) {
		if(deg[u[i]] == deg[v[i]]) g.add(v[i], u[i], 1, 1), a[u[i]]--, a[v[i]]++;
		else g.add(u[i], v[i], 1, 1), a[v[i]]--, a[u[i]]++;
	}
	for(int i = 1; i <= n; i++) {
		if(i <= n1) g.add(n + 1, i, 0, 1);
		else g.add(i, n + 2, 0, 1); 
	}
	int mxf = 0;
	for(int i = 1; i <= n + 2; i++) {
		if(a[i] > 0) {
			g.add(n + 3, i, 0, a[i]);
			mxf += a[i];
		}
		if(a[i] < 0) {
			g.add(i, n + 4, 0, -a[i]);
		}
	}
	g.add(n + 2, n + 1, 0, inf);
	Graph::Info s1 = g.stream(n + 3, n + 4);
	if(s1.fl != mxf) {
		cout << "Err s1 != mxf\n";
		exit(0);
	}
	s1.fl = g.e[g.en - 2].s;
	g.e[g.en - 1].s = 0;
	Graph::Info s2 = g.stream2(n + 1, n + 2);
	int res = m - (s1.cs + s2.cs);
	cout << res << '\n';
	for(int i = 0; i < g.en; i += 2) {
		if(g.e[i].s == 1 && g.e[i].u <= n && g.e[i].v <= n) {
			int u = g.e[i].u, v = g.e[i].v;
			f.add(v, u, 1, 1);
//			cout << v << "->" << u << '\n';
			id[u]++; od[v]++;
		}
	}
	for(int t = 1; t <= 3000; t++) {
		memset(vis, 0, sizeof(vis));
		x = y = 0;
		for(int i = 1; i <= n; i++) {
			if(id[i] >= 1 && od[i] >= 1) {
//				cout << "try " << i << endl;
				if(dfs(i)) break;
			}
		}
		vector<int> op[2];
		int p = 0;
		while(!tdl.empty()) {
			int u = tdl.front().fi, v = tdl.front().se;
			od[u]--, id[v]--;
			tdl.pop();
//			cout << u << "~" << v << '\n';
			if(u > v) swap(u, v);
			op[p].push_back(q[u][v].front()); q[u][v].pop();
			p ^= 1; 
		}
		if(!op[0].size()) continue;
//		cout << "A+";
		if(deg[u[op[0][0]]] != deg[v[op[0][0]]]) swap(op[0], op[1]);
		for(int x : op[0]) cout << x << ' '; for(int x : op[1]) cout << x << ' '; 
//		cout << '\n';
	}
	for(int t = 1; t <= 3000; t++) {
		memset(vis, 0, sizeof(vis));
//		for(int i = 1; i <= n; i++) {
//			cout << id[i] << ' ';
//		} cout << '\n';
		for(int i = 1; i <= n; i++) {
			if(id[i] == 0 && od[i] > 0) {
//				cout << "try " << i << '\n';
				if(dfs2(i)) break;
			}
		}
		vector<int> op[2];
		int p = 0;
		while(!tdl.empty()) {
			int u = tdl.front().fi, v = tdl.front().se;
			od[u]--, id[v]--;
//			cout << u << ' ' << v << '\n';
			tdl.pop();
			if(u > v) swap(u, v);
			op[p].push_back(q[u][v].front()); q[u][v].pop();
			p ^= 1; 
		}
		if(!op[0].size()) continue;
//		cout << "A+";
		for(int x : op[0]) cout << x << ' '; for(int x : op[1]) cout << x << ' '; //cout << '\n'; 
	}
}

signed main() {
	ios::sync_with_stdio(false); cin.tie(0);
	int _ = 1;
//	cin >> _;
	while(_--) work();
}