#include<stdio.h>

int main(){ long long int n,m,a; scanf("%lld %lld %lld",&n,&m,&a); long long int n1,m1; if(n%a>0){ n1 = n/a+1; }else{ n1 = n/a; } if(m%a>0){ m1 = m/a+1; }else{ m1 = m/a; } printf("%lld\n",n1*m1); return 0; }