n = int(input())
strings = []
for _ in range(n):
    buff = input().split("&")
    strings.append([int(buff[0]), int(buff[1]), "&".join(buff[2:])])

for elem in strings:
    s = ""
    a, b, string = elem
    for i in range(a, len(string), 2):
        s += string[i]
    s = s[:b]
    print(s)