8月5号团队赛补题

Berland Football Cup starts really soon! Commentators from all over the world come to the event.

Organizers have already built $\mathrm{nn commentary\; boxes. mm regional\; delegations\; will\; come\; to\; the\; Cup.\; Every\; delegation\; should\; get\; the same\; number of\; the\; commentary\; boxes.\; If\; any\; box\; is\; left\; unoccupied\; then\; the\; delegations\; will\; be\; upset. So\; each\; box\; should\; be\; occupied\; by\; exactly\; one\; delegation.}$

If $\mathrm{nn is\; not\; divisible\; by mm,\; it\; is\; impossible\; to\; distribute\; the\; boxes\; to\; the\; delegations\; at\; the\; moment.}$

Organizers can build a new commentary box paying $\mathrm{aa burles\; and\; demolish\; a\; commentary\; box\; paying bb burles.\; They\; can\; both\; build\; and\; demolish\; boxes\; arbitrary\; number\; of\; times\; (each\; time\; paying\; a\; corresponding\; fee).\; It\; is\; allowed\; to\; demolish\; all\; the\; existing\; boxes.}$

What is the minimal amount of burles organizers should pay to satisfy all the delegations (i.e. to make the number of the boxes be divisible by $\mathrm{mm)?}$

The only line contains four integer numbers $\mathrm{nn, mm, aa and bb (1\le n,m\le 10121\le n,m\le 1012, 1\le a,b\le 1001\le a,b\le 100),\; where nn is\; the\; initial\; number\; of\; the\; commentary\; boxes, mm is\; the\; number\; of\; delegations\; to\; come, aa is\; the\; fee\; to\; build\; a\; box\; and bb is\; the\; fee\; to\; demolish\; a\; box.}$

Output the minimal amount of burles organizers should pay to satisfy all the delegations (i.e. to make the number of the boxes be divisible by $\mathrm{mm).\; It\; is\; allowed\; that\; the\; final\; number\; of\; the\; boxes\; is\; equal\; to 00.}$

In the first example organizers can build $\mathrm{55 boxes\; to\; make\; the\; total\; of 1414 paying 33 burles\; for\; the\; each\; of\; them.}$

In the second example organizers can demolish $\mathrm{22 boxes\; to\; make\; the\; total\; of 00 paying 77 burles\; for\; the\; each\; of\; them.}$

In the third example organizers are already able to distribute all the boxes equally among the delegations, each one get $\mathrm{55 boxes.}$

$\mathrm{题目意思：足球赛之前要给每一支代表队分配评论框，每一支代表队都必须得到数量相同的评论框，现在有n个评论框，m支代表队，可以新建一些评论框代价是a，}$$\mathrm{也可以拆除一些评论框代价是b。问最后至少花费多少。}$

$\mathrm{解题思路：分别算出新建一些和拆除一些评论框的花费，找到最少的花费就行了。}$

#include<cstdio>
#include<cstring>
#include<algorithm>
#define ll long long int
using namespace std;
int main()
{
    ll n,m,a,b,x,y,ans1,ans2,ans;
    scanf("%lld%lld%lld%lld",&n,&m,&a,&b);
    x=n%m;
    y=n/m;
    ans1=x*b;///拆
    ans2=((y+1)*m-n)*a;//建
    ans=min(ans1,ans2);
    printf("%lld\n",ans);
    return 0;
}