#define _USE_MATH_DEFINES
#include<iostream>
#include<vector>
#include<algorithm>
#include<cmath>
#include<string>
#include<iomanip>
#include<numeric>
#include<queue>
#include<deque>
#include<stack>
#include<set>
#include<map>
#include<random>
#include<bitset>
#include<cassert>
#include<complex>
#include<fstream>
#include<cstdlib>
#include<functional>
using namespace std;
typedef long long ll;
const int mod=998244353;
const int dx[]={1,0,0,-1},dy[]={0,1,-1,0};
int arr[100000],ans[100000];
int main(){
	int n,k,a;
	char c;
	string s="RGB";
	cin>>n>>k;
	while(cin>>a>>c){
		a--;
		if(c=='G')
			arr[a]=1;
		if(c=='B')
			arr[a]=2;
	}
	for(int i=0;i<n;i++){
		if(i%3==0)
			ans[i]=arr[i];
		else if(i%3==1){
			if(ans[i-1]==arr[i])
				ans[i]=(arr[i]+1)%3;
			else
				ans[i]=arr[i];
		}else
			ans[i]=3-ans[i-1]-ans[i-2];
		cout<<s[ans[i]];
	}
	cout<<endl;
}