//https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 より
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

//

fn run() {
    input! {
        n: usize,
        p: [(i32, i32); n],
    }
    let mut map = std::collections::BTreeMap::new();
    for (i, &(mut x, mut y)) in p.iter().enumerate() {
        while y > 9 {
            y -= 9;
            x -= 5;
        }
        while x < 0 {
            x += 10;
        }
        while x >= 10 {
            x -= 10;
        }
        map.entry((x, y)).or_insert(vec![]).push(i);
    }
    let mut ans = vec![];
    for (_, p) in map {
        if ans.len() < p.len() {
            ans = p;
        }
    }
    assert!(ans.len() * 90 >= n);
    println!("{}", ans.len());
    for p in ans {
        print!("{} ", p + 1);
    }
    println!();
}

fn main() {
    run();
}