N=input()
S=input()
dp=[0]*3
dp[0]=1
mod=998244353
for s in S:
    prev=dp
    dp=[0]*3
    for i in range(3):
        for j,t in enumerate("ULR"):
            if (s=="." or s==t) and (i,j)!=(2,1):
                dp[j]+=prev[i]
                dp[j]%=mod
ans=sum(dp)%mod
print(ans)