#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N;
int X[303030],Y[303030];
vector<int> S[10][3][3];
void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N;
	FOR(i,N) {
		cin>>X[i]>>Y[i];
		x=X[i]/3;
		y=Y[i]/3;
		x-=y*3;
		x+=10*1000000;
		x%=10;
		S[x][X[i]%3][Y[i]%3].push_back(i);
	}
	
	FOR(x,3) FOR(y,3) FOR(i,10) if(S[i][x][y].size()*90>=N) {
		cout<<S[i][x][y].size()<<endl;
		FORR(s,S[i][x][y]) cout<<s+1<<" ";
		cout<<endl;
		return;
	}
	
		
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}