#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>
#include<utility>

using namespace std;

#define int long long
#define endl "\n"

constexpr long long INF = (long long)1e18;
constexpr long long MOD = 1'000'000'007; 

struct fast_io {
	fast_io(){
		std::cin.tie(nullptr);
		std::ios::sync_with_stdio(false);
	};
} fio;

signed main(){
	cout<<fixed<<setprecision(10);
	
	int N;
	vector<vector<vector<int>>> c(9, vector<vector<int>>(10));
	
	cin>>N;
	
	for(int i = 0; i < N; i++){
		int x, y;
		
		cin>>x>>y;
		
		x %= 18;
		y %= 10;
		
		if(x < 9) {
			c[x%9][y].emplace_back(i+1);
			
		} else {
			c[x%9][(y+5)%10].push_back(i+1);
		}
	}
	
	for(int i = 0; i< c.size(); i++){
		for(int j = 0; j < c[i].size(); j++){
			if(c[i][j].size() * 90 >= N) {
				cout<<c[i][j].size()<<endl;
				
				for(int k = 0; k < c[i][j].size(); k++){
					if(k) cout<<" ";
					cout<<c[i][j][k];
				}
				cout<<endl;
				return 0;
			}
		}
	}
	
	return 0;
}