/*
  Averin Maxim amax0703@gmail.com
*/
#define TASKNAME "escape"
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <algorithm>
#include <cassert>
#include <cmath>
#include <utility>
#include <map>
#include <set>
#include <vector>


#define MAXN int(1e5 + 10)
#define INF int(1e9)
#define pb push_back
#define mp make_pair
#define sz(A) (int)(A).size()
#define pi 3.1415926535897932384626433832795
#define sqr(a) ((a) * (a))
#define x fghsdhgjfshgkjfdhgjfs
#define y jhfjghjfdsghsjfd
#define out(x) cout<<(x)<<" " << "\n"
#define DB(x) cerr<<#x<<" = "<<(x)<<"\n"
#define DB2(a,b)   cerr<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<"\n"

using namespace std;
int ans = 0, n, s[MAXN], t[MAXN];
double timeP, timeW, t_out, v;

int main()
{
  #ifndef ONLINE_JUDGE
    freopen(TASKNAME".in", "r", stdin);
    freopen(TASKNAME".out", "w", stdout);
  #endif
  cin >> n;
  for(int i = 1; i <= n; i++)
    cin >> s[i] >> t[i];
  cin >> t_out >> v;
  for(int i = 1; i <= n; i++){
 //   DB(t_out + double(s[i])/v);
    if(t_out + double(s[i])/v <= double(t[i]) && ans == 0){
         ans = i;
         timeP = double(s[i])/double(v);
         timeW = double(t[i]) - timeP  - t_out;
         DB2(timeP, timeW);
    }
    else if(t_out + double(s[i])/v <= double(t[i])){
      if(double(s[i])/v < timeP && !(double(s[i]/v) == timeP && double(t[i]) - double(s[i])/v - t_out == timeW)){
        ans = i;
        timeP =  double(s[i])/v;
        timeW =  double(t[i]) - double(s[i])/v - t_out;
      }

    }
  }
  if(ans == 0)
    cout << -1;
  else
    cout << ans;
  return 0;
}