#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001

int main() {	
	
	int n,k;cin>>n>>k;
	
	vector<char> t(n,'-');
	rep(i,k){
		int a;
		char c;
		cin>>a>>c;
		
		t[a-1] = c;
	}
	
	string ans = "";
	int x =0,y=0,z=0;
	
	rep(i,n){
		int m = max({x,y,z});
		if(x==m&&y==m&&z==m)m++;
		bool f = true;
		if(t[i]=='-')f = true;
		else{
			if(t[i]=='R'){
				if(x!=m){
					x++;
					ans += 'R';
					continue;
				}
			}
			if(t[i]=='G'){
				if(y!=m){
					y++;
					ans += 'G';
					continue;
				}
			}
			if(t[i]=='B'){
				if(z!=m){
					z++;
					ans += 'B';
					continue;
				}
			}
		}
		
		if(x!=m){
			x++;
			ans += 'R';
		}
		else if(y!=m){
			y++;
			ans += 'G';
		}
		else{
			z++;
			ans += 'B';
		}
		
	}
	cout<<ans<<endl;
    return 0;
}