mod = 998244353

def solve():
	n, m = map(int, input().split())
	print((pow(pow(2, n, mod) - 1, m, mod) - (pow(pow(2, m, mod), n, mod) - pow(pow(2, m, mod) - 1, n, mod))) % mod)

t = int(input())
for _ in range(t):
	solve()