#include <cstdio>
#include <cstring>

int main() {
	char str[110];
	scanf("%s", str);
	str[strlen(str) - 8] = 0;
	puts(str);
	return 0;
}

#include "bits/stdc++.h"
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000


int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int R; cin >> R;
    if( R < 1200) cout << "ABC" << endl;
    else if (R < 2800) cout << "ARC" << endl;
    else cout << "AGC" << endl;

    return 0;
}
