305B - Continued Fractions - CodeForces Solution

import sys, random, bisect
from collections import deque, defaultdict
from heapq import heapify, heappop, heappush
from itertools import permutations
from math import gcd, log

input = lambda :sys.stdin.readline().rstrip()
mi = lambda :map(int, input().split())
li = lambda :list(mi())

p, q = mi()
n = int(input())
a = li()

g = gcd(p, q)
p, q = p // g, q // g

u, v, id = a[n - 1], 1, n - 2
while id >= 0:
    u, v = v, u
    u = a[id] * v + u
    id = id - 1

g = gcd(u, v)
u, v = u // g, v // g

if u == p and v == q: print('YES')
else: print('NO')