import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.math,
       std.algorithm;

void main()
{
    auto X = readln.strip.to!real;
    auto Y = readln.strip.to!real;
    auto L = readln.strip.to!real;

    long ans;
    ans += (X / L).abs.ceil + (Y / L).abs.ceil;
    if (X != 0 && Y >= 0) ans++;
    if (Y < 0) ans += 2;
    ans.writeln;
}