CodeForces 1A Theatre Square

A. Theatre Square

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

题目大意：有一个n * m的广场，现在要向广场上面铺地板，每一块地板都不能拆开，地板可以互相覆盖，问铺满广场至少需要多少块地板。

解题思路：由于 地板只能整块的铺，所以可以只考虑边上得情况，长宽的结果相乘即得答案。设长为n，宽为m，则需要ceil(n / a) * ceil(m / a)块木板。

代码如下：

#include <cstdio>
#include <cmath>

int main()
{
long long m,n,a;
long long l,w;
while(scanf("%I64d %I64d %I64d",&n,&m,&a) != EOF){
l = ceil((double)n / a);
w = ceil((double)m / a);
printf("%I64d\n",l * w);
}
return 0;
}