# n, m = map(int, input().split())
# ans = 0
# for bits in range(1 << (n*m)):
#     mat = [[0]*m for _ in range(n)]
#     for i in range(n):
#         for j in range(m):
#             if (bits >> (i*m+j)) & 1:
#                 mat[i][j] = 1
#     f = True
#     for i in range(n-1):
#         for j in range(m-1):
#             sm1 = 0
#             sm2 = 0
#             # (0,0)→(i,j)の和
#             for y in range(i+1):
#                 for x in range(j+1):
#                     sm1 += mat[y][x]
#             # (i+1, j+1)→(n-1,m-1)の和
#             for y in range(i+1, n):
#                 for x in range(j+1, m):
#                     sm2 += mat[y][x]
#             if sm1 % 2 == sm2 % 2:
#                 f = False
#     if f:
#         ans += 1
# print(ans)

# ×2
# 1 1→2
# 1 2→4
# 1 3→8
# 1 4→16
# 1 5→32

# ×2
# 2 2→8
# 2 3→16
# 2 4→32
# 2 5→64

# ×4
# 3 3→64
# 3 4→256
# 3 5→1024

# ×8
# 4 4→2048
# 4 5→16384

# n<m
# 1: 2 2 2 2...
# 2: 2 2 2 2...
# 3: 2 4 4 4...
# 4: 2 8 8 8...
# n-1回繰り返す.
# 2^max(1, n-1)

n, m = map(int, input().split())
if n > m:
    n, m = m, n
# (1, m)まで行く.
ans = pow(2, m, 998244353)
if n == 1:
    print(ans)
    exit()
if n == 2:
    print(ans*2 % 998244353)
    exit()
ans *= 2
ans %= 998244353
ans *= pow(pow(2, m-1, 998244353), n-2, 998244353)
ans %= 998244353
print(ans)