C++ :

#include<iostream>
#include<algorithm>
using namespace std;
const int N = 100005;
struct person{
	int id,score,power;
};
person a[2*N],win[N],lose[N];

bool comp(const person &x,const person &y){
	if (x.score!=y.score) return x.score>y.score;
	return x.id<y.id;
}

void swiss(int n){
	int i,j,k;
	for (k=i=j=1; k<=n; k++)
		if (a[2*k-1].power>a[2*k].power)
			a[2*k-1].score++,win[i++]=a[2*k-1],lose[j++]=a[2*k];
		else a[2*k].score++,win[i++]=a[2*k],lose[j++]=a[2*k-1];
	for (k=i=j=1; i<=n&&j<=n; k++)
		if (comp(win[i],lose[j])) a[k]=win[i++];
		else a[k]=lose[j++];
	while (i<=n) a[k++]=win[i++];
	while (j<=n) a[k++]=lose[j++];
}

int main(){
	int n,r,q;
	cin>>n>>r>>q;
	for (int i=1; i<=2*n; i++){
		cin>>a[i].score;
		a[i].id=i;
	}
	for (int i=1; i<=2*n; i++) cin>>a[i].power;
	sort(a+1,a+2*n+1,comp);
	for (int i=1; i<=r; i++) swiss(n);
	cout<<a[q].id<<endl;
	return 0;
}

Pascal :

var
   n,s,q,i,j,t,x:longint;
   a,c,p,b,d,e,f,h,g:array[0..500000]of longint;
procedure qsort(l,r:longint);
var
   i,j,mid,mid1,t:longint;
begin
 i:=l;j:=r;
 mid:=a[(i+j)div 2];
 mid1:=p[(i+j)div 2];
 while i<=j do
  begin
   while (a[i]>mid)or(a[i]=mid)and(p[i]<mid1)do inc(i);
   while (a[j]<mid)or(a[j]=mid)and(p[j]>mid1)do dec(j);
   if i<=j then
    begin
     t:=a[i];a[i]:=a[j];a[j]:=t;
     t:=c[i];c[i]:=c[j];c[j]:=t;
     t:=p[i];p[i]:=p[j];p[j]:=t;
     inc(i);dec(j);
    end;
  end;
 if l<j then qsort(l,j);
 if i<r then qsort(i,r);
end;
procedure marge;
var
   i,j,k:longint;
begin
 i:=1;j:=n+1;k:=1;
 while (i<=n)and(j<=n*2) do
  if (f[j]>f[i])or(f[j]=f[i])and(g[j]<g[i]) then
   begin b[k]:=f[j];d[k]:=h[j];e[k]:=g[j];inc(j);inc(k);end
  else begin b[k]:=f[i];d[k]:=h[i];e[k]:=g[i];inc(k);inc(i);end;
 while i<=n do
  begin b[k]:=f[i];d[k]:=h[i];e[k]:=g[i];inc(k);inc(i);end;
 while j<=n*2 do
  begin b[k]:=f[j];d[k]:=h[j];e[k]:=g[j];inc(k);inc(j);end;
 for i:=1 to n*2 do begin f[i]:=b[i];h[i]:=d[i];g[i]:=e[i];end;
end;
begin
 readln(n,s,q);
 for i:=1 to n*2 do read(a[i]);
 for i:=1 to n*2 do
  begin
   read(c[i]);
   p[i]:=i;
  end;
 qsort(1,n*2);
 for i:=1 to s do
  begin
   for j:=1 to n do
    begin
     x:=j*2;
     if c[x-1]>c[x] then
      begin
       inc(a[x-1]);
       f[j]:=a[x-1];f[j+n]:=a[x];
       g[j]:=p[x-1];g[j+n]:=p[x];
       h[j]:=c[x-1];h[j+n]:=c[x];
      end
     else
      begin
       inc(a[x]);
       f[j]:=a[x];f[j+n]:=a[x-1];
       g[j]:=p[x];g[j+n]:=p[x-1];
       h[j]:=c[x];h[j+n]:=c[x-1];
      end;
    end;
   marge;
   for j:=1 to n*2 do begin a[j]:=f[j];p[j]:=g[j];c[j]:=h[j];end;
  end;
 writeln(p[q]);
end.