A9028 | Continued Fractions

A continued fraction of height $n$ is a fraction of form . You are given two rational numbers, one is represented as  and the other one is represented as a finite fraction of height $n$ . Check if they are equal.

The first line contains two space-separated integers $p,q$ $(1<=q<=p<=10^{18})$ — the numerator and the denominator of the first fraction.

The second line contains integer $n$ $(1<=n<=90)$ — the height of the second fraction. The third line contains $n$ space-separated integers $a_{1},a_{2},...,a_{n}$ $(1<=a_{i}<=10^{18})$ — the continued fraction.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

Print "YES" if these fractions are equal and "NO" otherwise.