A. Theatre Square time limit per test2 seconds memory limit per test64 megabytes inputstandard input outputstandard 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.

Sample test(s) input 6 6 4 output 4

测试数据较大,要用double,注意要控制cout对double的输出格式,std::fixed可以禁止科学计数法,setprecision控制输出小数位数

cout<<std::fixed<<setprecision(0)<<(double)( (int)((m-1)/a)+1 )*(double)( (int)((n-1)/a)+1 );

注意是先减1再整除