#include<bits/stdc++.h>
using namespace std;

#define gcd(a,b)		__gcd(a,b)
#define lcm(a,b)		(a*b)/gcd(a,b)
#define ff              first
#define ss              second
#define int             long long
#define float			double
#define pb              emplace_back
#define mp              make_pair
#define pii             pair<int,int>
#define vi              vector<int>
#define vc				vector<char>
#define vb				vector<bool>
#define vf				vector<float>
#define vs				vector<string>
#define mii             map<int,int>
#define seti			set<int>
#define pqb             priority_queue<int>
#define pqs             priority_queue<int,vi,greater<int> >
#define setbits(x)      __builtin_popcountll(x)
#define zrobits(x)      __builtin_ctzll(x)
#define mod             1000000007
#define inf             INT64_MAX
#define ps(x,y)         fixed<<setprecision(y)<<x
#define mk(arr,n,type)  type *arr=new type[n];
#define w(x)            int x; cin>>x; while(x--)
#define all(x)			x.begin(),x.end()
#define digits(x)		floor(log10(x))+1
#define FIO				ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)

template<class T>
void printV(vector<T> a) {
	for (auto v : a)cout << v << " ";
}
template<class T>
void readV(vector<T>& a , int n) {
	for (int i = 0 ; i < n ; i++)cin >> a[i];
}
template<class T>
void printA(T* a , int n) {
	for (int i = 0; i < n  ; i++)cout << a[i] << " ";
}
template<class T>
void readA(T* a , int n) {
	for (int i = 0 ; i < n ; i++)cin >> a[i];
}



class dsu {
private:
	int *id;
	int* sz;

	int root(int i) {
		while (i != id[i]) {
			id[i] = id[id[i]];
			i = id[i];
		}
		return i;
	}
public:
	int n;
	dsu(int v) {
		n = v;
		id = new int[n];
		sz = new int[n];

		for (int i = 0; i < n; i++) {
			id[i] = i;
			sz[i] = 0;
		}
	}

	bool find(int p , int q) {
		return root(p) == root(q);
	}

	void join(int p , int q) {
		int i = root(p);
		int j = root(q);
		if (i == j) {
			return;
		}
		if (sz[i] < sz[j]) {
			id[i] = j ;
			sz[j] += sz[i];
		}
		else {
			id[j] = i;
			sz[i] += sz[j];
		}
	}
};

class BIT {
private:
	int* FT;
	int n;

public:
	void updateBIT(int index , int val) {
		index += 1;
		while (index <= n) {
			FT[index] += val;
			index += (index & (-index));
		}
	}

	int getSum(int index) {
		index += 1;
		int sum = 0 ;
		while (index > 0) {
			sum += FT[index];
			index -= (index & (-index));
		}
		return sum;
	}


	BIT(int* a , int v) {
		n = v ;
		FT = new int[n + 1];
		for (int i = 1 ; i <= n ; i++) {
			FT[i] = 0 ;
		}
		for (int i = 0 ; i < n ; i++) {
			updateBIT(i, a[i]);
		}
	}

};

int nCr(int n , int r ) {
	int p = 1, k = 1;

	if (n - r < r ) {
		r = n - r;
	}
	if (r != 0) {
		while (r != 0) {
			p *= n ;
			k *= r ;
			int m = __gcd(p, k);
			p /= m;
			k /= m;
			n--;
			r--;
		}
	}
	else {
		p = 1;
	}
	return p ;
}

int modPower(int x, int y , int p) {
	//Used to calculate (x^y)%p
	int res = 1;
	if (y == 0) {
		return 1;
	}

	x = x % p;
	if (x == 0) {
		return 0  ;
	}

	while (y > 0) {
		if (y & 1) {
			res = (res * x) % p;
		}

		y >>= 1;
		x = (x * x) % p;
	}
	return res ;

}



int32_t main() {
	FIO;

	int x, k, d;
	cin >> x >> k >> d;


	if (x > 0) {
		float sub = (1.0 * x) / d;
		int v = floor(sub + 1) ;
		x -= (min(k, v) * d);
		k -= min(k, v);

		if (k & 1) {
			x += d;
		}
	}
	else {
		float add = (-1.0 * x) / d;
		int v = floor(add + 1);
		x += (min(k, v) * d);
		k -= min(v, k);

		if (k & 1) {
			x -= d;
		}
	}
	cout << abs(x);





	return 0;
}


Measured memory_bytes: 3756