def main():
    
    n = int(input())
    s = list(input())
    mod = 998244353
    dp = [[0,0] for _ in range(n+1)]
    dp[0][0] = 1
    
    for i in range(n):
        if s[i] == "0":
            dp[i+1][0] = dp[i][0]+dp[i][1]
        else:
            dp[i+1][1] = dp[i][0]+dp[i][1]
        dp[i+1][1] += dp[i][1]
        dp[i+1][0] %= mod
        dp[i+1][1] %= mod
        
    print(dp[-1][1])
    
if __name__ == '__main__':
    main()