#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n][2];
  for (int i = 0; i < n; i++) {
    cin >> a[i][0] >> a[i][1];
  }
  int sum1 = 0;
  int sum2 = 0;
  for (int i = 0; i < n; i++) {
    if (abs(sum1 + a[i][0] - sum2) <= 500) {
      sum1 += a[i][0];
      a[i][0] = -1;
    } else {
      sum2 += a[i][1];
    }
  }
  if (abs(sum1 - sum2) > 500) {
    cout << "-1";
  } else {
    for (int i = 0; i < n; i++) {
      if (a[i][0] == -1) {
        cout << "A";
      } else {
        cout << "G";
      }
    }
  }
  return 0;
}
