A. Theatre Square

 

                                          A. Theatre Square

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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

实现思路：此题应该用面积来判断到底需要几块矩形石板，并考虑数据过大的情况用 longlong 或者 __int64

Input

1000000000 1000000000 1

Output

1000000000000000000

代码如下：

//A. Theatre Square
#include<iostream>
using namespace std;
int main(){
    long long m,n,a;
    cin>>m>>n>>a;
    long long t=1;
    if(m<=a||n<=a)
        t*=1;
    if(m>a){
        if(m%a==0)
            t*=m/a;
            else t*=m/a+1;
    }

    if(n>a){
        if(n%a==0)
            t*=n/a;
        else t*=n/a+1;
    }

    cout<<t<<endl;
}