#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int suma = 0, sumg = 0, a, g;
  char *arr = new char[n];
  for (int i = 0; i < n; i++) {
    scanf("%d %d", &a, &g);
    if (abs(suma + a - sumg) < abs(sumg + g - suma)) {
      suma += a;
      arr[i] = 'A';
    } else {
      sumg += g;
      arr[i] = 'G';
    }
  }
  if (abs(suma - sumg) > 500)
    cout << "-1";
  else
    for (int i = 0; i < n; i++) cout << arr[i];
  cout << endl;
  return 0;
}
