1A-THEATRE SQUARE by Petr

1A-THEATRE  SQUARE

ref : http://codeforces.com/problemset/problem/1/A

My approach got "TLE" coz i used two loops which ranges upto 10^9.(But i donno how many test cases will it pass if i wont get "TLE" :p

Then after having a glance at Petr's code(just saw he used a formula - donno what at that time ;) ),

So i too tried to solve/to find a formula.

I came up with this : 

ceil(n/a)*ceil(m/a)

which is not true - it failed in a test case

but finally solved it using the same formula and it turns out that i failed coz of precision 

Test: #16, time: 15 ms., memory: 1812 KB, exit code: 0, checker exit code: 1, verdict: WRONG_ANSWER

Input

1000000000 1000000000 999999999

Output

1

Answer

4

Checker Log

wrong answer 1st numbers differ - expected: '4', found: '1'

But Petr solved this in constant time by using simple formula :

                  ((n + a - 1) / a) * ((m + a - 1) / a)

I missed a-1 in both numerators :(