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

    /*------------------------------------------------------------------*/

    #define ll long long int
    #define mp make_pair
    #define pb push_back
    #define MOD 1000000007

    bool isvowel(char c)
    {
        if(c=='a'||c=='e'||c=='i'||c=='o'||c=='u')
            return true;
            return false;
    }
    ll isprime(ll n)
    {
        ll ans=1;
        for(ll i=2;i<=sqrt(n);i++)
        {
            if(n%i==0)
                ans = i;
        }
        return ans;
    }
    ll power(ll a,ll b,ll m)
    {
        if(b==0)
            return 1;
        if(b==1)
            return a%m;
        ll temp=power(a,b/2,m);
        if(b%2==0)
            return ((temp%m)*(temp%m))%m;
        else
            return ((((temp%m)*(temp%m))%m)*a%m)%m;
    }

    /*-----------------------------------------------------------------------------*/

    ll c(ll n, ll k)
    {
        ll C[n + 1][k + 1];
        ll i, j;

        for (i = 0; i <= n; i++)
        {
            for (j = 0; j <= min(i, k); j++)
            {

                if (j == 0 || j == i)
                    C[i][j] = 1;

                else
                    C[i][j] = (C[i - 1][j - 1]%MOD +
                            C[i - 1][j])%MOD;
            }
        }
        return C[n][k]%MOD;
    }
    ll modInverse(ll a, ll m)
    {
        ll m0 = m;
        ll y = 0, x = 1;

        if (m == 1)
        return 0;

        while (a > 1)
        {

            ll q = a / m;
            ll t = m;
            m = a % m, a = t;
            t = y;


            y = x - q * y;
            x = t;
        }
        if (x < 0)
        x += m0;

        return x;
    }
    ll func(ll n)
    {
        ll ans=0;
        for(ll i=2;i*i<=n;i++)
        {
            if(n%i==0)
            {
                if(i/10==0)
                    ans+=1+func(i)*func(n/i);
                else
                    ans+=func(i)*func(n/i);
            }
        }
        return ans;
    }
    ll dp[205][205][205];
    ll check(ll red[],ll gre[],ll blu[],ll r,ll g,ll b,ll i,ll j,ll k)
    {
    if(dp[i][j][k]!=-1)
        return dp[i][j][k]; 
    if(i<r&&j<g&&k<b)
    {
        return dp[i][j][k]=max(red[i]*gre[j]+check(red,gre,blu,r,g,b,i+1,j+1,k),max(gre[j]*blu[k]+check(red,gre,blu,r,g,b,i,j+1,k+1),blu[k]*red[i]+check(red,gre,blu,r,g,b,i+1,j,k+1)));
    }
    else if(i<r&&j<g) 
    {
        return dp[i][j][k]=red[i]*gre[j]+check(red,gre,blu,r,g,b,i+1,j+1,k);
    }
    else if(j<g&&k<b)
    {
        return dp[i][j][k]=gre[j]*blu[k]+check(red,gre,blu,r,g,b,i,j+1,k+1);
    }
    else if(i<r&&k<b)
    {
        return dp[i][j][k]=red[i]*blu[k]+check(red,gre,blu,r,g,b,i+1,j,k+1);
    }
    else
    {
        return 0;
    }
    }
    int main()
    {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);

        //freopen("1.txt","rt",stdin);
        //freopen("output.txt","wwt",stdout);

        ll t;
        t=1;
        //cin>>t;
        //ll t1=0;
        while(t--)
        {
            ll x,k,d,ans;
            cin>>x>>k>>d;
            x = abs(x);
            ll req = x/d;

            if(req >= k)
            {
                ans=abs(x-k*d);
            } 
            else
            {
                ll p=x/d;
                k-=p;
                if(k%2==0)
                ans=x - p*d;
                else
                {
                    ans=abs(x-(p+1)*d);
                }
            }
            cout<<ans<<endl;
        }
    }


Measured memory_bytes: 3604