def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    T = int(input[idx])
    idx += 1
    for _ in range(T):
        N = int(input[idx])
        A = int(input[idx+1])
        W = int(input[idx+2])
        K = int(input[idx+3])
        idx +=4
        
        numerator = A - K + 1
        if K == 0:
            print(":(")
            continue
        if numerator < 0:
            print(":(")
            continue
        X_max = numerator // K
        if X_max < 0:
            print(":(")
            continue
        required = K * X_max + (K -1)
        if required > A:
            print(":(")
        else:
            print(X_max)
        
if __name__ == "__main__":
    main()