import sys

N = int(sys.stdin.readline())
MOD = 998244353

x = 1
y = 0

for c in sys.stdin.buffer.readline():
	if c == 49:
		y += x
		if y >= MOD:
			y -= MOD
		x = 0
	x += y
	if x >= MOD:
		x -= MOD

print(y)