from decimal import Decimal

X,Y = map(int,input().split())
N = int(input())
A = list(map(int,input().split()))

X = Decimal(X*1000) / Decimal('3600')
Y = Decimal(Y*1000) / Decimal('3600')

for i in range(N-1) :
    t = Decimal(A[i]) / Decimal(X)
    c = Decimal(t*Y)
    if A[i+1] < c :
        print("NO")
        break
else :
    print("YES")