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

DP0=[[0]*(2*N+3) for i in range(N+1)]
DP1=[[0]*(2*N+3) for i in range(N+1)]
F=1
for i in range(N):
  if S[i]=='1':
    for j in range(-N,N+1):
      DP1[i+1][j]=(DP1[i][j]+DP0[i][j])%mod
  elif S[i]=='0':
    for j in range(-N,N+1):
      DP0[i+1][j-1]=(DP0[i+1][j-1]+DP0[i][j])%mod
      DP0[i+1][j+1]=(DP0[i+1][j+1]+DP1[i][j])%mod
    if F:
      F=0
      DP0[i+1][0]=(DP0[i+1][0]+1)%mod
  else:
    for j in range(-N,N+1):
      DP1[i+1][j]=(DP1[i][j]+DP0[i][j])%mod
    for j in range(-N,N+1):
      DP0[i+1][j-1]=(DP0[i+1][j-1]+DP0[i][j])%mod
      DP0[i+1][j+1]=(DP0[i+1][j+1]+DP1[i][j])%mod
    if F:
      DP0[i+1][0]=(DP0[i+1][0]+1)%mod
for i in range(1,N+1,2):
  F+=(DP0[N][i]+DP1[N][i])
print(F%mod)