 time limit per test: 1 second
 memory limit per test: 256 megabytes
 input: standard input
 output: standard output
Theatre Square in the capital city of Berland has a rectangular shape with the size n × m meters. On the occasion of the city’s anniversary, a decision was taken to pave the Square with square granite flagstones. Each flagstone is of the size a × a.
What is the least number of flagstones needed to pave the Square? It’s allowed to cover the surface larger than the Theatre Square, but the Square has to be covered. It’s not allowed to break the flagstones. The sides of flagstones should be parallel to the sides of the Square.
Input
The input contains three positive integer numbers in the first line: n, m and a (1 <= n, m, a <= ${10^9}).
Output
Write the needed number of flagstones.
Examples
1  6 6 4 
1  4 
Notice
in this problem, you should pay attention to define the variables m, n and a. i use ‘int’ in my first submit. it note me “Wrong answer on test 9”, because when you input 999999999 999999999 1, the number can’t be solved. then i change the ‘int’ to ‘unsigned long long’ and it told me ‘Accepted’.
My Code
1 

 Post title：1ATheatre_Square
 Post author：leenickzh
 Create time：20210910 23:00:27
 Post link：https://nickk.cn/2021/09/10/1ATheatreSquare/
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