#include<bits/stdc++.h>
using namespace std;
namespace file_read{
    namespace input_file_io{
        char ib[1<<25],*ip1=ib,*ip2=ib;
        inline char gc(){
#ifdef JohnAlfnov
			return getchar();
#else
            return (ip1==ip2&&(ip2=(ip1=ib)+fread(ib,1,1<<24,stdin)),ip1==ip2?EOF:*ip1++);
#endif
        }
        inline int read(){
            int x=0;
            char c=gc();
            while(c<'0'||c>'9')c=gc();
            while(c>='0'&&c<='9'){
                x=(x<<3)+(x<<1)+(c^'0');
                c=gc();
            }
            return x;
        }
    };
    namespace output_file_io{
        char ob[1<<23],*op=ob;
        inline void pc(char c){
            *op++=c;
        }
        void write(int x){
            if(x<0){
                pc('-');
                x=-x;
            }
            if(x==0)pc('0');
            static int number_stack[40];
            int total_count=0;
            while(x)number_stack[++total_count]=x%10,x/=10;
            while(total_count){
                pc(number_stack[total_count]+'0');
                --total_count;
            }
        }
        inline void final_write(){
            fwrite(ob,op-ob,1,stdout);
    	}
    };
	using namespace input_file_io;
	using namespace output_file_io;
};
using namespace file_read;
int n,S,T;
int hd[5000005],mw[5000005],l[5000005],pre[5000005];
int nxt[12000005],c[12000005],bb[12000005],tt[12000005],tot=1;
inline void addedge(int u,int v,int w,int bh){
	if(!hd[u])hd[u]=++tot;
	else nxt[mw[u]]=++tot;
	mw[u]=tot;
	c[tot]=w,bb[tot]=bh,tt[tot]=v;
}
int q[5000005];
bool bfs(){
	for(int i=1;i<=n;++i)l[i]=1e9+7,pre[i]=hd[i];
	l[S]=1;
	int h=0,t=-1;
	q[++t]=S;
	while(h<=t){
		int x=q[h++];
		for(int i=hd[x];i;i=nxt[i]){
			int v=tt[i];
			if(c[i]==0)continue;
			if(l[v]>l[x]+1){
				l[v]=l[x]+1;
				if(v==T)return 1;
				q[++t]=v;
			}
		}
	}
	return 0;
}
int ans=0;
int dinic(int x,int rl){
	if(x==T)return rl;
	int he=0;
	for(int i=pre[x];i;i=nxt[i]){
		pre[x]=i;
		if(c[i]==0)continue;
		int v=tt[i];
		if(l[v]!=l[x]+1)continue;
		int ll=dinic(v,min(c[i],rl));
		rl-=ll,he+=ll;
		c[i]-=ll,c[i^1]+=ll;
		if(!rl)return he;
	}
	return he;
}
bool vist[2000005];
int main(){
	int aa=clock();
	int n1=read(),n2=read(),m=read();
	n=1+n1+n2+1;
	S=1,T=n;
	for(int i=1;i<=n1;++i)addedge(S,1+i,1,0),addedge(1+i,S,0,0);
	for(int i=1;i<=n2;++i)addedge(1+n1+i,T,1,0),addedge(T,1+n1+i,0,0);
	for(int t=1;t<=m;++t){
		int u=read(),v=read();
		addedge(1+u,1+n1+v,1,t);
		addedge(1+n1+v,1+u,0,0);
	}
	for(int i=1;i<=19;++i){
		if(!bfs())break;
		if(1.0*(clock()-aa)/CLOCKS_PER_SEC>3.4)break;
		ans+=dinic(S,INT_MAX);
	}
	write(ans),pc('\n');
	for(int i=2;i<=1+n1;++i)for(int j=hd[i];j;j=nxt[j]){
		if(c[j])continue;
		int dd=tt[j];
		if(dd<2+n1||dd>1+n+n1)continue;
		vist[bb[j]]=1;
	}
	for(int i=1;i<=m;++i)if(vist[i])write(i),pc('\n');
	final_write();
	return 0;
}