use std::io::Write;
use std::collections::*;

type Map<K, V> = BTreeMap<K, V>;
type Set<T> = BTreeSet<T>;
type Deque<T> = VecDeque<T>;

fn run() {
    input! {
        n: usize,
        k: usize,
        p: [(usize1, String); k],
    }
    let mut c = vec!['.'; n];
    for (x, s) in p {
        c[x] = s.chars().next().unwrap();
    }
    let mut ans = String::new();
    for c in c.chunks(3) {
        let mut p = vec!['R', 'G', 'B'];
        p.sort();
        for _ in 0..6 {
            let mut ok = true;
            for (i, c) in c.iter().enumerate() {
                if *c == '.' {
                    ok &= p[..=i].contains(&c);
                }
            }
            if ok {
                break;
            }
            next_permutation(&mut p);
        }
        ans.extend(p.into_iter());
    }
    ans.truncate(n);
    println!("{}", ans);
}

fn main() {
    run();
}

// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[macro_export]
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_export]
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_export]
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")
    };
}
// ---------- end input macro ----------
// ---------- begin next_permutation ----------
fn next_permutation<T: Ord>(a: &mut [T]) -> bool {
    a.windows(2).rposition(|a| a[0] < a[1]).map_or(false, |x| {
        let y = a.iter().rposition(|b| a[x] < *b).unwrap();
        a.swap(x, y);
        a[(x + 1)..].reverse();
        true
    })
}
// ---------- end next_permutation ----------