#include <iostream>

#define ll long long 
#include <cmath>
using namespace std;

int main(){



float n, m, a;
// int res = 0;
scanf("%f %f %f", &n, &m, &a);


if ( a > n && a > m ){
	cout << 1 << '\n';
}
else{

	if (  (a>=n&&!(a>=m))|| (!(a>=n)&&(a>=m))){
		cout << 2 << '\n';
	}
	else{
		float half1=n/2, half2=m/2, res = 0, area1 = n * m, area2 = a * a;

		
		//cout << "half1 is " << half1 << ", half2 is " << half2 << " and a is " << a << '\n';
		if (  (a >= half1 && !( a >= half2) )|| ( !(a >= half1) &&  a >= half2 )){
		
			res = ( (  area1 / area2  - 0.5 ) == ceil( area1 / area2 )  ) ? ceil( area1 / area2 ) + 2 : ceil( area1 / area2 ); 
			
			cout << res << '\n'; 
		}
		else if ( a < half1 && a < half2 ) {
			// in the case of 'a' being smaller than the halves of both lengths	
			ll area3 = area1, area4 = area2;
			if ( area3 % area4 == 0 ){
				res = area1 / area2; 
				cout << res << '\n';
			}
			else{
				res =( area1 / area2 ) + area3 % area4;
				cout << res << '\n';	
			}
		}
		else{
		
			// float res2 = area1 / area2;
			cout << 4 << '\n';	
		}
		// printf("%lld\n", res);
	}
}

}