#include<bits/stdc++.h>
	using namespace std;
	#define ll long long
	#define n_l '\n'

	#ifndef ONLINE_JUDGE
	#define dbg(...) cout << "[" << #__VA_ARGS__ << "]: "; cout << to_string(__VA_ARGS__) << endl
	template <typename T, size_t N> int SIZE(const T (&t)[N]){ return N; } template<typename T> int SIZE(const T &t){ return t.size(); } string to_string(const string s, int x1=0, int x2=1e9){ return '"' + ((x1 < s.size()) ? s.substr(x1, x2-x1+1) : "") + '"'; } string to_string(const char* s) { return to_string((string) s); } string to_string(const bool b) { return (b ? "true" : "false"); } string to_string(const char c){ return string({c}); } template<size_t N> string to_string(const bitset<N> &b, int x1=0, int x2=1e9){ string t = ""; for(int __iii__ = min(x1,SIZE(b)),  __jjj__ = min(x2, SIZE(b)-1); __iii__ <= __jjj__; ++__iii__){ t += b[__iii__] + '0'; } return '"' + t + '"'; } template <typename A, typename... C> string to_string(const A (&v), int x1=0, int x2=1e9, C... coords); int l_v_l_v_l = 0, t_a_b_s = 0; template <typename A, typename B> string to_string(const pair<A, B> &p) { l_v_l_v_l++; string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; l_v_l_v_l--; return res; } template <typename A, typename... C> string to_string(const A (&v), int x1, int x2, C... coords) { int rnk = rank<A>::value; string tab(t_a_b_s, ' '); string res = ""; bool first = true; if(l_v_l_v_l == 0) res += n_l; res += tab + "["; x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v)); auto l = begin(v); advance(l, x1); auto r = l; advance(r, (x2-x1) + (x2 < SIZE(v))); for (auto e = l; e != r; e = next(e)) { if (!first) { res += ", "; } first = false; l_v_l_v_l++; if(e != l){ if(rnk > 1) { res += n_l; t_a_b_s = l_v_l_v_l; }; } else{ t_a_b_s = 0; } res += to_string(*e, coords...); l_v_l_v_l--; } res += "]"; if(l_v_l_v_l == 0) res += n_l; return res; } void dbgm(){;} template<typename Heads, typename... Tails> void dbgm(Heads H, Tails... T){ cout << to_string(H) << " | "; dbgm(T...); } 
	#define dbgm(...) cout << "[" << #__VA_ARGS__ << "]: "; dbgm(__VA_ARGS__); cout << endl
	#endif

	#define pb push_back
	#define all(x) (x).begin(),(x).end()
	#define fi first
	#define se second
	#define sz(x) ((int)(x).size())
	#define forn(i,n) for(int i=0;i<n;i++)
	#define for1(i,n) for(int i=1;i<=n;i++)
	typedef vector<int> vi;
	typedef vector<ll> vl;
	typedef pair<int,int> pii;
	typedef double db;
	typedef vector<vi> vvi;
	const ll mod=1000000007;
	const ll N=200005; //check this
	int dx[] = {-1, 0, 1, 0, 1, 1, -1, -1};
	int dy[] = {0, -1, 0, 1, 1, -1, 1, -1};

	ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
	ll powb(ll a,ll b) {ll res=1;a ; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a;a=a*a;}return res;}
	ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}

	int main(){
	    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

	    #ifndef ONLINE_JUDGE
	    freopen("inputf.in", "r", stdin);
	    freopen("outputf.in", "w", stdout);
	    #endif

	    int t=1;
	    // cin>>t;
	    while(t--){
	    	ll x,k,d;cin>>x>>k>>d;
	    	if(x<0)x=-x;
	    	if(k>=x/d){
	    		k-=x/d;
	    		ll val=x-x/d*d;
	    		// cout<<k<<endl;
	    		if(k%2==0)cout<<abs(val);
	    		else cout<<abs(val-d);
	    	}else{
	    		cout<<x-k*d;
	    	}

		}
	}


Measured memory_bytes: 3620