Min. cost flow

#pragma comment(linker, "/STACK:65777216")
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <queue>
#include <string>
#include <memory.h>
#include <iterator>
#define y1 trololoy1
#define y0 trololoy0
#define mem(A,X) memset(A,X,sizeof(A))
#define memo(A) memset(A,0,sizeof(A))
#define forn(I,B) for (int I=1;I<=(B);I++)
#define forg(H,V) for (int H=first[V];h;h=next[H])
#define rep(I,B) for (int I=0;I<(B);I++)
#define labs(X) (((X)>0)?(X):(-(X)))
#define ropen(X) freopen(X,"r",stdin)
#define wopen(X) freopen(X,"w",stdout)
#define rwopen(X) freopen(X".in","r",stdin);freopen(X".out","w",stdout)
#define pb push_back
#define mp make_pair
#define all(X) (X).begin(),(X).end()
#define sqr(X) ((X)*(X))

using namespace std;

typedef pair <int,int> pii;
typedef double ld;
typedef long long ll;
typedef pair <ll,ll> pll;
typedef vector<int> vi;
const int N=222;
const int M=55555;
const int INF=111111111;
const double eps=1e-9;
const double pi=3.14159265358979;

int ef[M],es[M],first[N],next[M],ev[M],ec[M],S=220,T=221,a[N],b[N],x,y,z,c,n,sum1,sum2,ans,from[N],edge[N],d[N];

inline int be(int x){
    return (x&1)?x+1:x-1;
}

inline void add(int x,int y,int z,int co){
    next[++c]=first[x];first[x]=c;
    ef[c]=x;es[c]=y;ev[c]=z;ec[c]=co;
}

void create_graph(){
    forn(i,n){
        add(S,i,a[i],0);
        add(i,S,0,0);
    }
    forn(i,n) forn(j,n){
        add(i,100+j,INF,labs(i-j)*z);
        add(100+j,i,0,-labs(i-j)*z);
        add(i,100+j,INF,x+y);
        add(100+j,i,0,-x-y);
    }
    forn(i,n){
        add(100+i,T,b[i],0);
        add(T,100+i,0,0);
    }
}

inline bool find_path(){
    mem(d,63);
    d[S]=0;
    forn(i,n+n+2) forn(j,c){
        if (!ev[j]) continue;
        if (d[es[j]]>d[ef[j]]+ec[j] && d[ef[j]]<1000000000){
            d[es[j]]=d[ef[j]]+ec[j];
            from[es[j]]=ef[j];
            edge[es[j]]=j;
        }
    }
    return d[T]<1000000000;
}

int main(){
    rwopen("landscape");
    scanf("%d%d%d%d",&n,&x,&y,&z);
    forn(i,n){
        scanf("%d%d",&a[i],&b[i]);
        sum1+=a[i];
        sum2+=b[i];
    }
    if (sum1>sum2) ans=(sum1-sum2)*y;
    else ans=(sum2-sum1)*x;
    create_graph();
    while (find_path()){
        int q=INF;
        for (int v=T;v!=S;v=from[v]) q=min(q,ev[edge[v]]);
        ans+=q*d[T];
        for (int v=T;v!=S;v=from[v]){
            ev[edge[v]]-=q;
            ev[be(edge[v])]+=q;
        }
    }
    printf("%d\n",ans);
    return 0;
}