A. Theatre Square

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 ≤ 10⁹).

Output

Write the needed number of flagstones.

Examples

input

6 6 4

output

4

需要注意越界,可能出现10¹⁸。因此尽量用long long。 编写此程序时出现失误，long与long long是不同的。

#include 
     
      #include 
      
       using namespace std;int main(int argc, char *argv[]){    long n,m,a;    cin>>n>>m>>a;    long long width = ceil(((double)m)/a);    long long height = ceil(((double)n)/a);    cout<
       
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