C++ :

#include<iostream>
#include<algorithm>
using namespace std;
const int N(5005);
int t[N],f[N],c[N];
//ifstream cin("batch.in");
//ofstream cout("batch.out");
int main()
{
    int n,s;
    cin>>n>>s;
    for (int i=1;i<=n;i++)
    {
        cin>>t[i]>>f[i];
        t[i]+=t[i-1];
        f[i]+=f[i-1];
    }
    fill(c+1,c+n+1,0x7fffffff); 
    for (int k=1;k<=n;k++)
        for (int i=1;i<=k;i++)
            c[k]=min(c[k],c[i-1]+s*(f[n]-f[i-1])+t[k]*(f[k]-f[i-1]));
    cout<<c[n]<<endl;
    return 0;
}

Pascal :

var n,s,i,k:longint;
    t:array[0..5005]of longint;
    f:array[0..5005]of longint;
    c:array[0..5005]of longint;
begin
     readln(n);
     readln(s);
     for i:=1 to 5004 do c[i]:=10000;
     for i:=1 to n do
     begin
       read(t[i],f[i]);
       t[i]:=t[i-1]+t[i];
       f[i]:=f[i-1]+f[i];
     end;
     for k:=1 to n do
         for i:=1 to k do
             if(c[k]>c[i-1]+s*(f[n]-f[i-1])+t[k]*(f[k]-f[i-1]))
             then c[k]:=c[i-1]+s*(f[n]-f[i-1])+t[k]*(f[k]-f[i-1]);
     writeln(c[n]);
     readln;
     readln;
end.