Theatre Square_Codeforces_1A

原题链接：http://codeforces.com/problemset/problem/1/A

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

重点：保证全覆盖时所用砖块面积可能大于需要覆盖的面积，因此将长、宽分别计算。

#include

using namespace std;

int main()
{
    long long n, m, a;
    scanf("%lld%lld%lld", &m, &n, &a);
    long long len, wid;
    len = m / a;
    wid = n / a;
    if(m % a)
        len++;
    if(n % a)
        wid++;
    printf("%lld", len*wid);
    return 0;
}