import sys

def solve():
    input_data = sys.stdin.read().split()
    if not input_data:
        return
    
    n = int(input_data[0])
    s = input_data[1]
    MOD = 998244353

    res = 1
    for i in range(n - 1):
        if s[i] == '0' and s[i+1] == '1':
            res = (res * 2) % MOD
            
    print(res)

if __name__ == "__main__":
    solve()