N = int(input())
S = input()
MOD = 998244353

dp = [1,0,0]
for c in S:
    ndp = [0,0,0]
    if c == 'L':
        ndp[0] = sum(dp[:2]) % MOD
    elif c == 'U':
        ndp[1] = sum(dp) % MOD
    elif c == 'R':
        ndp[2] = sum(dp) % MOD
    else:
        ndp[0] = sum(dp[:2]) % MOD
        ndp[1] = sum(dp) % MOD
        ndp[2] = sum(dp) % MOD
    dp = ndp
print(sum(dp) % MOD)