mod = 998244353
N = int(input())
S = list(input())
dp = [ [0 for i in range(3)] for _ in range(N)]

if S[0]=="L":
    dp[0][0] = 1
elif S[0]=="R":
    dp[0][1] = 1
elif S[0]=="U":
    dp[0][2] = 1
else:
    dp[0][0] = 1
    dp[0][1] = 1
    dp[0][2] = 1
for i in range(1, N):
    if S[i]=="L":
        dp[i][0] = dp[i-1][0]+dp[i-1][2]
    elif S[i]=="R":
        dp[i][1] = dp[i-1][0]+dp[i-1][1]+dp[i-1][2]
    elif S[i]=="U":
        dp[i][2] = dp[i-1][0]+dp[i-1][1]+dp[i-1][2]
    else:
        dp[i][0] = dp[i-1][0]+dp[i-1][2]
        dp[i][1] = dp[i-1][0]+dp[i-1][1]+dp[i-1][2]
        dp[i][2] = dp[i-1][0]+dp[i-1][1]+dp[i-1][2]
    for j in range(3):
        dp[i][j] %= mod
#for i in range(N):
#    print(dp[i])
print(sum(dp[-1])%mod)