#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int getCmdCntToGoal(int cdir, int ddir, int cpos, int dpos, int l)
{
	int cmdCnt = 0;
	if (cpos==dpos) {
		return 0;
	}
	if (cdir!=ddir) {
		if ( (cdir==0 || cdir==2) && (ddir==1 || ddir==3) ) {
			cmdCnt += 1;
		}
		else  {
			cmdCnt += 2;
		}
	}
	while(cpos!=dpos) {
		int len = min(abs(dpos-cpos), l) * (dpos<0?-1:1);
		cpos += len;
		++ cmdCnt;
	}
	return cmdCnt;
}

int main(int argc, char**argv)
{
	int gx, gy, l;
	cin >> gx >> gy >> l;

	int dstXdir = (gx>0 ? 1 : 3);
	int dstYdir = (gy>0 ? 0 : 2);

	int cmdCnt = 0;
	cmdCnt += getCmdCntToGoal(      0, dstYdir, 0, gy, l);
	cmdCnt += getCmdCntToGoal(dstYdir, dstXdir, 0, gx, l);

	cout << cmdCnt << endl;
	return 0;
}