#include<bits/stdc++.h>

 using namespace std;

 typedef long long ll;

 void exgcd(ll a,ll b,ll& x,ll& y,ll& g) {

     if(!b)x=,y=,g=a;

     else exgcd(b,a%b,y,x,g),y-=x*(a/b);

 }

 ll solve(double x1,double y1,double x2,double y2) {

     if(x1>x2||(x1==x2&&y1>y2))swap(x1,x2),swap(y1,y2);

     if(x1==x2&&y1==y2) {

         if(x1==round(x1)&&x2==round(x2))return ;

         else return ;

     } else if(x1==x2) {

         if(x1==round(x1))return floor(y2)-ceil(y1)+;

         else return ;

     } else if(y1==y2) {

         if(y1==round(y1))return floor(x2)-ceil(x1)+;

         else return ;

     } else {

         ll a=round((y2-y1)*),b=round((x1-x2)*),c=round((y2*x1-y1*x2)*);

         ll x,y,g;

         exgcd(a,b,x,y,g);

         if(c%g==) {

             x*=c/g;

             ll bb=abs(b/g);

             ll xl=ceil(x1),xr=floor(x2);

             ll xll=x+(xl-x)/bb*bb;

             ll xrr=x+(xr-x)/bb*bb;

             if(xll<xl)xll+=bb;

             if(xrr>xr)xrr-=bb;

             return max(0ll,(xrr-xll)/bb+);

         } else return ;

     }

 }

 int main() {

     ll T;

     scanf("%lld",&T);

     while(T--) {

         double x1,y1,x2,y2;

         scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);

         printf("%lld\n",solve(x1,y1,x2,y2));

     }

     return ;

 }