N=int(input())
S=input()

mod=998244353

DP0=[0]*(N+1)
DP1=[0]*(N+1)
DP2=[0]*(N+1)

DP0[0]=1

for i in range(N):
    if S[i]=="L":
        DP1[i+1]=DP0[i]+DP1[i]
    elif S[i]=="R":
        DP2[i+1]=DP0[i]+DP1[i]+DP2[i]
    elif S[i]=="U":
        DP0[i+1]=DP0[i]+DP1[i]+DP2[i]
    else:
        DP0[i+1]=DP0[i]+DP1[i]+DP2[i]
        DP1[i+1]=DP0[i]+DP1[i]
        DP2[i+1]=DP0[i]+DP1[i]+DP2[i]

    DP0[i+1]%=mod
    DP1[i+1]%=mod
    DP2[i+1]%=mod

print((DP0[-1]+DP1[-1]+DP2[-1])%mod)