CF1A Theatre Square

A.
Theatre Squaretime limit per test

2 secondsmemory limit per test

64 megabytesinput

standard inputoutput

standard output

Theatre Square in the capital city of Berland has a rectangular shape with the sizen × 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 sizea × 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 ≤ 10^9).

Output

Write the needed number of flagstones.

Sample test(s)Input

6 6 4

Output

4解題思路：該題是簡單題，只要讀懂題目即可。要使n*m的面積被a*a的方塊覆蓋，可以突出。也就是說，只要x*a>=n,y*a>=m即可，後面要輸出的是x*y。為避免資料溢出，只要把資料類型轉換，然後用lld輸出即可。 
#include<stdio.h>int main(){    int n,m,a;    while(scanf("%d%d%d",&n,&m,&a)!=EOF)    {        int x,y;        x=n/a;        if(n%a!=0) x++;        y=m/a;        if(m%a!=0) y++;        printf("%lld\n",(long long)x*y);    }    return 0;}