#include<bits/stdc++.h> using namespace std; #define rep(i,a,b) for(int i=a;i<b;i++) using ll = long long; #define all(p) p.begin(),p.end() int main(){ int N; cin>>N; vector<vector<int>> p(90); rep(i,0,N){ int x,y; cin>>x>>y; int A=(x%9)*10+(x*5+y)%10; p[A].push_back(i+1); } for(auto x:p){ if(N<=90*(int)(x.size())){ cout<<x.size()<<"\n"; rep(i,0,(int)x.size()){ if(i) cout<<" "; cout<<x[i]; } cout<<"\n"; return 0; } } assert(false); }