// what is matter? never mind. 
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
#define int long long
#define i128 __int128
#define ull unsigned long long
#define SZ(x) ((int)((x).size()))
#define ALL(x) (x).begin(),(x).end()
using namespace std;
inline i128 read()
{
    char c=getchar();i128 x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}
void write(__int128 x){
	// print a __int128 variable
	if(x < 0){putchar('-'); x = -x;}
	if(x > 9)write(x / 10);
	putchar(x % 10 + '0');
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;
 
#define maxn 100005
#define inf 0x3f3f3f3f

int n,k,tx,ty;
int x[maxn],y[maxn];
int res,INF=4e18;

int l,r;
void add(int a,int b){
//	cout<<"add "<<a<<" "<<b<<"\n";
	if(a==0){
		if(b>0) l=1,r=0;
		return;
	}
	if(a>0) {
		if(b>=0) l=max(l,(b+a-1)/a);
	}
	else {
		a=-a,b=-b;
		if(b>=0) r=min(r,b/a);
		else l=1,r=0;
	}
}

void work()
{
	n=read(),k=read(),tx=read(),ty=read();
	res=INF;
	For(i,0,n-1){
		x[i]=read(),y[i]=read();
		if(i)x[i]+=x[i-1],y[i]+=y[i-1];
	}
	For(i,0,n-1){
		l=0,r=INF+5;
		int xx=tx,yy=ty;
		if(i) xx-=x[i-1],yy-=y[i-1];
		for(int k1:{1,-1}) for(int k2:{1,-1}) {
			int a=k*n+x[n-1]*k1+y[n-1]*k2;
			int b=-k*i+xx*k1+yy*k2;
			add(a,b);
		}
//		cout<<"i,l,r "<<i<<" "<<l<<" "<<r<<"\n";
		if(l<=r)res=min(res,l*n+i);
	}
	if(res>=INF)res=-1;
	cout<<res<<"\n";
}

signed main()
{
	int T=read();
	while(T--)work();
	return 0;
}
/*
1 2
5 2 3
1 1 2 3 7
1 1 0 3 2
1 1 1
1
0
*/