#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <climits>
#include <cmath>
#include <complex>
#include <cstring>
#include <deque>
#include <functional>
#include <iostream>
#include <iomanip>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#include <cstdint>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> pii;
#define MP make_pair
#define PB push_back
#define inf 1000000007
#define rep(i,n) for(int i = 0; i < (int)(n); ++i)
#define all(x) (x).begin(),(x).end()

template<typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val){
    std::fill( (T*)array, (T*)(array+N), val );
}
 
template<class T> inline bool chmax(T &a, T b){
    if(a<b){
        a = b;
        return true;
    }
    return false;
}

template<class T> inline bool chmin(T &a, T b){
    if(a>b){
        a = b;
        return true;
    }
    return false;
}

int main(){
    int n;
    cin >> n;
    vector<int> p[90];
    rep(i,n){
        int a,b;
        cin >> a >> b;
        int k = b/9;
        int aa  = a%10;
        int bb  = b%9;
        if(k%2==0){
           p[10*bb+aa].push_back(i+1); 
        }else{
           p[10*bb+(aa+5)%10].push_back(i+1);
        }
    }
    int mx = 0;
    int id = 0;
    rep(i,90){
        if(chmax(mx,(int)p[i].size())){
            id = i;
        }
    }
    cout << p[id].size() << endl;
    for(auto x:p[id]){
        cout << x << " ";
    }
    cout << endl;
    return 0;
}