#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <array>
#include <atcoder/modint>

using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(int)(n); i++)


const i64 INF = 1001001001001001001;
using modint = atcoder::static_modint<998244353>;

int main(){
    int N, K; cin >> N >> K;
    string S(N, 'R');
    rep(i,N){
        int p; cin >> p; p--;
        cin >> S[p];
    }
    rep(i,N){
        if(i % 3 == 1){
            if(S[i] == S[i-1]){
                if(S[i-1] == 'R') S[i] = 'B';
                else S[i] = 'R';
            }
        }
        if(i % 3 == 2){
            S[i] = 'R' ^ 'B' ^ 'G' ^ S[i-1] ^ S[i-2];
        }
    }

    cout << S << endl;
    return 0;
}


struct ios_do_not_sync{
    ios_do_not_sync(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
    }
} ios_do_not_sync_instance;