990A - Commentary Boxes - CodeForces Solution

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/*
* * * * * * * * *     * * * * * *       * * * * * *       * * * * * * * *   * * *       * * *
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 * * * * * * * * *   * * * * * * * *   * * * * * * *           * * *        * * * * * * * * *
 * * * * * * * * *   * * * * * * * *   * * * * *               * * *        * * * * * * * * *
 * * *               * * *     * * *   * * * * * *             * * *        * * *       * * *
 * * *               * * *     * * *   * * *  * * *            * * *        * * *       * * *
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 * * *               * * *     * * *   * * *     * * *         * * *        * * *       * * *
 
*/
 
//=======================^========================================================^=======================\\
 
#include<iostream>
#include<math.h>
#include<stdlib.h>
// #include<bits/stdc++.h>
#include<string.h>
#include<ctype.h>
#include<set>
#include<vector>
#include <algorithm>
#include<map>
#define test ll t;cin>>t;while(t--)
#define ll long long int
#define lld long double
#define setfor for(auto it: s1)
#define parthparekh ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define fi(l,r) for(ll i = l; i < r; i++)
#define fj(l,r) for(ll j = l; j < r; j++)
#define fk(l,r) for(ll k = l; k < r; k++)
#define fir(r,l) for(ll i=r;i>=l;i--)
#define fjr(r,l) for(ll j=r;j>=l;j--)
#define pb push_back
#define em emplace_back
#define yy cout<<"YES\n"
#define nn cout<<"NO\n"
using namespace std;
int main()
{
    parthparekh;
    ll n,m,a,b,ans=0,ans1=0;
    cin>>n>>m>>a>>b;
    if(n%m==0)
    cout<<0<<endl;
    else
    {
        ans=(n%m)*b;
        ans1=(m-(n%m))*a;
        cout<<min(ans,ans1)<<endl;
    }
}