#include<bits/stdc++.h>
#define pa pair<int,int>
#define mp make_pair
#define fi first
#define se second
#define ll long long 
#define ull unsigned long long
#define LL __int128
#define int ll
#define poly vector<int>
using namespace std;
const int N=100005;
int f[N][4],x[N],y[N];
int n,m,X,Y;
inline int calc(int x,int y,int z)
{
    if (x==0) return 0;
    if (y<0) x*=-1,y*=-1;
    if (z==0)
    {
        if (x>0) return x/y;
        return (x-y+1)/y;
    }
    if (z==1)
    {
        if (x>0) return (x+y-1)/y;
        return x/y;
    }
}
void BellaKira()
{
    n=100000,m=100000,X=100000000,Y=100000000;
    cin>>n>>m>>X>>Y;
    //trans to zfx
    {
        int nx=X,ny=Y;
        X=nx-ny,Y=nx+ny;
    }
    for (int i=1;i<=n;i++)
    {
        x[i]=1038,y[i]=-12323;
        cin>>x[i]>>y[i];
    }
    if (X==0&&Y==0)
    {
        cout<<0<<'\n';
        return;
    }
    for (int i=1;i<=n;i++)
    {
        // cout<<"?"<<i<<" "<<x[i]<<" "<<y[i]<<endl;
        for (int j=0;j<4;j++) f[i][j]=f[i-1][j];
        f[i][0]+=x[i]-y[i]-m;
        f[i][1]+=x[i]+y[i]-m;
        f[i][2]+=x[i]-y[i]+m;
        f[i][3]+=x[i]+y[i]+m;
        if (X>=f[i][0]&&X<=f[i][2]&&Y>=f[i][1]&&Y<=f[i][3])
        {
            cout<<i<<'\n';
            return;
        }
    }
    int xl=f[n][0],xr=f[n][2];
    int yl=f[n][1],yr=f[n][3];
    int extans=0,ans=1e18;
    for (int i=1;i<=n;i++)
    {
        int nxl=f[i][0],nxr=f[i][2];
        int nyl=f[i][1],nyr=f[i][3];
        int lm=0,rm=1e18;

        // xl*m<=(X-nxl) xr*m>=(X-nxr)
        if (xr==0&&nxr<X)
        {
            continue;
        }
        if (xl==0&&nxl>X) 
        {
            continue;
        }
        if (xr>0) lm=max(lm,calc(X-nxr,xr,1));
        if (xr<0) rm=min(rm,calc(X-nxr,xr,0));

        if (xl<0) lm=max(lm,calc(X-nxl,xl,1));
        if (xl>0) rm=min(rm,calc(X-nxl,xl,0));

        // m<=(Y-nyl)/(yl) m>=(Y-nyr)/yr
        if (yr==0&&nyr<Y)
        {
            continue;
        }
        if (yl==0&&nyl>Y) 
        {
            continue;
        }
        if (yr>0) lm=max(lm,calc(Y-nyr,yr,1));
        if (yr<0) rm=min(rm,calc(Y-nyr,yr,0));

        if (yl<0) lm=max(lm,calc(Y-nyl,yl,1));
        if (yl>0) rm=min(rm,calc(Y-nyl,yl,0));

        if (lm<=rm)
        {
            extans=1;
            ans=min(ans,lm*n+i);
        }
    }
    if (extans) cout<<ans<<'\n';
    else cout<<"-1\n";
}
signed main()
{
  
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T=10;
    cin>>T;
    while (T--)
    {
        BellaKira();
    }
}