#include <bits/stdc++.h>
using namespace std;
const double pi = 3.1415926535897;
long long ceil(long long a, long long b) {
  if (a < 0) return a / b;
  if (a % b == 0)
    return a / b;
  else
    return a / b + 1;
}
void solve() {
  long long n;
  cin >> n;
  long long a[n], g[n];
  long long suma = 0, sumg = 0;
  for (long long i = 0; i < n; i++) {
    cin >> a[i] >> g[i];
    suma += a[i];
    sumg += g[i];
  }
  long long g1 = ceil(suma - 500, 1000), g2 = (suma + 500) / 1000;
  long long a1 = ceil(sumg - 500, 1000), a2 = (sumg + 500) / 1000;
  g1 = max((long long)0, g1);
  a1 = max((long long)0, a1);
  g2 = min(n, g2);
  a2 = min(n, a2);
  long long g22 = n - a1, g12 = n - a2;
  if (g22 < g1 or g2 < g12) {
    cout << "-1\n";
    return;
  }
  long long numG;
  if (g1 <= g12)
    numG = g2;
  else
    numG = g22;
  for (long long i = 0; i < numG; i++) cout << "G";
  for (long long i = 0; i < n - numG; i++) cout << "A";
  cout << endl;
}
int main() {
  long long t = 1;
  for (int i = 1; i <= t; i++) solve();
}
