Codeforces Beta Round #1 A. Theatre Square

A. Theatre Square

time limit per test

2 seconds

memory limit per test

64 megabytes

input

standard input

output

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 ≤ 10⁹).

Output

Write the needed number of flagstones.

Sample test(s)

Input

6 6 4

Output

4题意理解：给定面积为n*m 的 广场，有a*a 的砖块，问至少要多少砖块才能完全覆盖广场。技巧：向上取整---> ceil();code:
#include <iostream>#include <cstdio>#include <algorithm>#include <string.h>#include <cmath>using namespace std;int main(){    long long n,m,a;    long long l,w;    scanf("%I64d%I64d%I64d",&n,&m,&a);    long long sum =ceil( m*1.0/a)*ceil(n*1.0/a);        printf("%I64d\n",sum);    return 0;}