import sys

def solve():
    input_data = sys.stdin.read().split()
    if len(input_data) < 2:
        return
    
    n = int(input_data[0])
    s = input_data[1]
    MOD = 998244353

    dp = [0] * (n + 1)
    dp[0] = 1
    
    last_zero = -1
    
    for i in range(1, n + 1):
        char = s[i-1]
        dp[i] = dp[i-1]
        
        if char == '1':
            if last_zero != -1:
                dp[i] = (dp[i] + dp[last_zero]) % MOD
        else:
            last_zero = i - 1
            
    print(dp[n])

if __name__ == "__main__":
    solve()