#include <bits/stdc++.h>
using namespace std;
struct bigint {
  int a[3000];
  void mult(unsigned long long t) {
    unsigned long long g = 0;
    for (int i = (1); i <= (3000 - 1); i++) {
      g += t * a[i];
      a[i] = g % 10;
      g /= 10;
    }
  }
  void plus(const bigint &s) {
    int g = 0;
    for (int i = (1); i <= (3000 - 1); i++) {
      g += a[i] + s.a[i];
      a[i] = g % 10;
      g /= 10;
    }
  }
};
unsigned long long d[100];
bigint up, down, tmp;
void lemon() {
  unsigned long long p, q;
  cin >> p >> q;
  int n;
  cin >> n;
  for (int i = (1); i <= (n); i++) cin >> d[i];
  memset(up.a, 0, sizeof up.a);
  up.a[1] = 1;
  memset(down.a, 0, sizeof down.a);
  down.a[1] = 1;
  up.mult(d[n]);
  for (int i = (n - 1); i >= (1); i--) {
    swap(up, down);
    tmp = down;
    tmp.mult(d[i]);
    up.plus(tmp);
  }
  up.mult(q);
  down.mult(p);
  for (int i = (1); i <= (3000 - 1); i++)
    if (up.a[i] != down.a[i]) {
      cout << "NO" << endl;
      return;
    }
  cout << "YES" << endl;
}
int main() {
  ios::sync_with_stdio(true);
  lemon();
  return 0;
}
