用的是分类讨论的方法，判断从什么时候开始 $x/y$ 风向变为做 正/负 贡献

$6,7,9,10$ 号点在不该输出 -1 的地方输出了 -1

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
#define int __int128

#define lyx return
#define AKIOI 0
const int one=1;
const int INF=(one<<126);

inline int read(){
	int ret=0;
	char ch=' ',c=getchar();
	while(!('0'<=c&&c<='9')) ch=c,c=getchar();
	while('0'<=c&&c<='9') ret=(ret<<1)+(ret<<3)+(c^48),c=getchar();
	return ch=='-'?-ret:ret;
}

inline int absll(int x){ return x<0?-x:x; }

void read(int &x){
	// read a __int128 variable
	char c; bool f = 0;
	while(((c = getchar()) < '0' || c > '9') && c != '-');
	if(c == '-'){f = 1; c = getchar();}
	x = c - '0';
	while((c = getchar()) >= '0' && c <= '9')x = x * 10 + c - '0';
	if(f) x = -x;
}
void write(int x){
	// print a __int128 variable
	if(x < 0){putchar('-'); x = -x;}
	if(x > 9)write(x / 10);
	putchar(x % 10 + '0');
}
int min(int x,int y){ return x<y?x:y; }
int max(int x,int y){ return x>y?x:y; }

int T;
int n,k,x,y;
const int N=1e5+10;
int xx[N],yy[N];
int dx[N],dy[N];

signed main(){
//	freopen("6.in","r",stdin);
//	freopen("wind.out","w",stdout);
	read(T);
	while(T--){
		read(n),read(k),read(x),read(y);
		if(x==0&&y==0){
			for(int i=1;i<=n;i++) read(x),read(y);
			printf("0\n");
			continue;
		}
		int wk=0,mi=INF,ans;
		bool flag=false;
		for(int i=1;i<=n;i++){
			read(xx[i]),read(yy[i]);
			dx[i]=dx[i-1]+xx[i];
			dy[i]=dy[i-1]+yy[i];
			wk+=k;
			int cost=absll(dx[i]-x)+absll(dy[i]-y);
			if(cost<=wk&&flag==false){
				flag=true;
				write(i);
				putchar('\n');
			}
		}
		int ki=k;
		k*=n;
		const int dxn=dx[n],dyn=dy[n];
		if(flag) continue;
		int xt,yt,mi1,mi2;
		for(int i=1;i<=n;i++){
			if((dx[i]<=x&&dxn<=0)||(dx[i]>=x&&dxn>=0)) xt=-1;
			else xt=absll(x-dx[i])/absll(dxn);
			if((dy[i]<=y&&dyn<=0)||(dy[i]>=y&&dyn>=0)) yt=-1;
			else yt=absll(y-dy[i])/absll(dyn);
			mi1=min(xt,yt);
			mi2=max(xt,yt);
			int cost=absll(dx[i]-x)+absll(dy[i]-y)-ki*i;
//			printf("xt=%lld yt=%lld cost=%lld\n",xt,yt,cost);
			
			int work1=absll(dxn)+absll(dyn)+k;
			if(work1<=0) continue;
			int tim=(cost-1)/work1+1;
//			printf("work1=%lld tim=%lld\n",work1,tim);
			if(tim<=mi1){
				if(tim<mi) mi=tim,ans=i;
				else if(tim==mi&&i<ans) ans=i;
				continue;
			}
			
			if(mi1!=-1){
				cost-=mi1*work1;
				dx[i]+=mi1*dxn,dy[i]+=mi1*dyn;
				if(mi1==xt) cost+=absll(dx[i]+dxn-x)-absll(dx[i]-x);
				else cost-=absll(dxn);
				if(mi1==yt) cost+=absll(dy[i]+dyn-y)-absll(dy[i]-y);
				else cost-=absll(dyn);
				tim=mi1+1;
				dx[i]+=dxn,dx[i]+=dyn;
				if(cost<=k){
					if(tim<mi) mi=tim,ans=i;
					else if(tim==mi&&i<ans) ans=i;
					continue;
				}
				cost-=k;
			}
			else tim=0;
			
			int work2=(tim>xt?-1:1)*absll(dxn)+(tim>yt?-1:1)*absll(dyn)+k;
			if(work2<=0) continue;
			tim+=(cost-1)/work2+1;
//			printf("work2=%lld tim=%lld\n",work2,tim);
			if(tim<=mi2){
				if(tim<mi) mi=tim,ans=i;
				else if(tim==mi&&i<ans) ans=i;
				continue;
			}
			
			if(mi2!=-1){
				if(mi1==-1) mi1=0;
				cost-=(mi2-mi1)*work2;
				dx[i]+=(mi2-mi1)*dxn,dy[i]+=(mi2-mi1)*dyn;
				if(mi2==xt) cost+=absll(dx[i]+dxn-x)-absll(dx[i]-x);
				else cost+=absll(dxn);
				if(mi2==yt) cost+=absll(dy[i]+dyn-y)-absll(dy[i]-y);
				else cost+=absll(dyn);
				tim=mi2+1;
				dx[i]+=dxn,dy[i]+=dyn;
				if(cost<=k){
					if(tim<mi) mi=tim,ans=i;
					else if(tim==mi&&i<ans) ans=i;
					continue;
				}
				cost-=k;
			}
			else tim=0;
			
			int work3=k-absll(dxn)-absll(dyn);
			if(work3<=0) continue;
			tim+=(cost-1)/work3+1;
			if(tim<mi) mi=tim,ans=i;
			else if(tim==mi&&i<ans) ans=i;
		}
		if(mi==INF) printf("-1");
		else write(mi*n+ans);
		putchar('\n');
	}
	lyx AKIOI;
}