import sys
if sys.platform =='ios':
	import clipboard
	a=clipboard.get()
	a = a.split('\n')
	text = '\n'.join(a)
	with open('input_file.txt','w') as f:
		f.write(text)
	sys.stdin = open('input_file.txt')
	
x,y = map(int,input().split())
N = int(input())
a = list(map(int,input().split()))
X = x/3.6
Y = y/3.6

dis = 0
ans = "YES"
for i in range(N-1):
	s = a[i]/X
	dis = (Y-X)*s
	if (round((a[i+1]-a[i]),6) < round(dis,6)):
		ans = "NO"
		break
		
print(ans)