t = int(input())
results = []
for _ in range(t):
    n = int(input())
    s = input()
    s = s.strip()
    s = s.replace(" ","")
    reversed_s = s[::-1]
    results.append(reversed_s)
    
for result in results:
    print(result)

去掉空格： s = s.replace(" ","")