N = int(input())
S = list(input())
mod = 998244353
pre0, pre1 = 1, 0
for s in S:
    dp0, dp1 = 0, 0
    s = int(s)
    if s == 0:
        dp0 += pre0 + pre1
        dp1 += pre1
    else:
        dp0 += pre0 + pre1
        dp1 += pre0 + pre1
    dp0 %= mod
    dp1 %= mod
    dp0, pre0 = pre0, dp0
    dp1, pre1 = pre1, dp1
    
print(pre1)