N = int(input())
customers = [int(i) for i in input().split()]

results = [0 for _ in range(N+1)]
# contient num. cust suivi de:
# 0: jsp
# 1: forcément G
# 2: forcément S

stack = [] # alt, vu
def depop(action):
    seen = False
    for i, (el, se) in enumerate(reversed(stack)):
        if el == action:
            del stack[len(stack)-i-1]
            if se and seen:
                raise ValueError
            elif se:
                return 1 # G
            elif seen:
                return 2 # S
            return 1 # G

        stack[len(stack)-i-1] = (el, True)
        seen = True

def load_results():
    for action in customers:
        #print(action, stack)
        if action > 0:
            stack.append((abs(action), False))
        else:
            results[abs(action)] = depop(abs(action))

try:
    load_results()
    for i in results[1:]:
        if i==0:
            print("U", end="") # Unknown
        elif i==1:
            print("G", end="")
        else:
            print("S", end="")
    print()
except ValueError:
    print("*")