A. Theatre Square（math）

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

水题但是错了n次，归其原因还是对C语言不太熟悉，很多东西我还都不知道——int64，什么时候用这个，真的不太了解，未来的路还很长，加油

AC代码

#include<stdio.h>
#include<math.h>

int main()
{
    __int64 n,m,a;
    __int64 L,W;

    scanf("%I64d%I64d%I64d",&n,&m,&a);
    if( n%a == 0 )
        L = n/a;
    else
        L = n/a + 1;

    if( m%a == 0 )
        W = m/a;
    else
        W = m/a + 1;

    printf("%I64d
", W*L);

    return 0;
}