#include<stdio.h>

 #include<math.h>

 double len(double x1,double y1,double x2,double y2){

     return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));

 }

 int main(){

     int T;

     while(scanf("%d",&T)!=EOF){

         for(int q=;q<=T;q++){

             double x1,y1,x2,y2;

             double a,b,c;

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

             a=len(,,x1,y1);

             b=len(,,x2,y2);

             c=len(x1,y1,x2,y2);

             double cos1=(a*a+b*b-c*c)/(*a*b);

             double t=acos(cos1)*/3.14159;

             printf("%.2lf\n",t);

         }

     }

     return ;

 }

 #include<stdio.h>

 int main(){

     int N;

     while(scanf("%d",&N)!=EOF){

         for(int q=;q<=N;q++){

             char a[];

             scanf("%s",a);

             printf("");

             for(int i=;i<=;i++)printf("%c",a[i]);

             printf("\n");

             getchar();

         }

     }

     return ;

 }