#include <stdio.h>

int main() {
    long long n,m,a;
    scanf("%lld%lld%lld",&n,&m,&a);
    long long chang,kuan,count;
    chang=(n+a-1)/a;
    kuan=(m+a-1)/a;
    count=chang*kuan;
    printf("%lld",count);
    return 0;
}

向上取整
a/b==(a+b-1)/b