import sys


def debug(*args):
    print(*args, file=sys.stderr)


n = int(input())
s = input()

dp_l = [0]*n
dp_r = [0]*n
dp_up = [0]*n

if s[0] == 'L':
    dp_l[0] = 1
elif s[0] == 'R':
    dp_r[0] = 1
elif s[0] == 'U':
    dp_up[0] = 1
else:
    dp_l[0] = 1
    dp_r[0] = 1
    dp_up[0] = 1

for i in range(1, n):
    if s[i] == 'L':
        dp_l[i] = dp_l[i-1] + dp_up[i-1]
        dp_r[i] = 0
        dp_up[i] = 0
    elif s[i] == 'R':
        dp_l[i] = 0
        dp_r[i] = dp_l[i-1] + dp_r[i-1] + dp_up[i-1]
        dp_up[i] = 0
    elif s[i] == 'U':
        dp_l[i] = 0
        dp_r[i] = 0
        dp_up[i] = dp_l[i-1] + dp_r[i-1] + dp_up[i-1]
    else:
        dp_l[i] = dp_l[i-1] + dp_up[i-1]
        dp_r[i] = dp_l[i-1] + dp_r[i-1] + dp_up[i-1]
        dp_up[i] = dp_l[i-1] + dp_r[i-1] + dp_up[i-1]
    dp_l[i] %= 998244353
    dp_r[i] %= 998244353
    dp_up[i] %= 998244353

print((dp_l[-1]+dp_r[-1]+dp_up[-1])%998244353)