#include<cstdio>
#include<cstring>
using namespace std;
const int N=2000005,M=N<<3;
int n1,n2,m,cnt,S,T;
int to[M],nxt[M],f[M],h[N<<1];
void add(int i,int x,int y,int z){
	to[i]=y;f[i]=z;nxt[i]=h[x];h[x]=i;
}
int cur[N<<1],dep[N<<1];
int que[N<<1],op,cl;
bool bfs(){
	memset(dep,0,sizeof dep);
	memcpy(cur,h,sizeof cur);
	op=0;cl=1;que[1]=S;dep[S]=1;
	while(op<cl){
		int x=que[++op];
		for(int i=h[x],y;i;i=nxt[i]){
			y=to[i];
			if(!f[i]) continue;
			if(!dep[y]){
				dep[y]=dep[x]+1;
				que[++cl]=y;
			}
			if(y==T) return true;
		}
	}
	return false;
}
int min1(int x,int y){
	return x<y?x:y;
}
int dfs(int x,int lim){
	if(x==T) return lim;
	int flow=lim,k;
	for(int &i=cur[x],y;i;i=nxt[i]){
		y=to[i];
		if(dep[y]==dep[x]+1 and f[i]){
			k=dfs(y,min1(f[i],flow));
			flow-=k;f[i]-=k;f[i^1]+=k;
			if(!flow) break;
		}
	}
	if(flow) dep[x]=0;
	return lim-flow;
}
int main(){
	scanf("%d%d%d",&n1,&n2,&m);
	S=n1+n2+1;T=S+1;cnt=1;
	for(int i=1,x,y;i<=m;i++){
		scanf("%d%d",&x,&y);
		add(++cnt,x,y+n1,1);
		add(++cnt,y+n1,x,0);
	}
	for(int i=1;i<=n1;i++){
		add(++cnt,S,i,1);
		add(++cnt,i,S,0);
	}
	for(int i=1;i<=n2;i++){
		add(++cnt,i+n1,T,1);
		add(++cnt,T,i+n1,0);
	}
	int ans=0;
	if(n<=10000){
		while(bfs()) ans+=dfs(S,min1(n1,n2));
	}else{
		if(bfs()) ans+=dfs(S,min1(n1,n2));
	}
	printf("%d\n",ans);
	for(int i=1;i<=m;i++){
		if(!f[i<<1]) printf("%d\n",i);
	}
	return 0;
}

answer.code: In function ‘int main()’:
answer.code:64:12: error: ‘n’ was not declared in this scope
   64 |         if(n<=10000){
      |            ^
answer.code:48:14: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   48 |         scanf("%d%d%d",&n1,&n2,&m);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~
answer.code:51:22: warning: ignoring return value of ‘int scanf(const char*, ...)’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
   51 |                 scanf("%d%d",&x,&y);
      |                 ~~~~~^~~~~~~~~~~~~~