#include<stdio.h> #include <algorithm> using namespace std; bool cmp(double x,double y) { return x<y; } int main(){int t,n,i;double x[1010],y[1010],a[1010];scanf("%d",&t);while(t--){scanf("%d",&n);for(i=1;i<=n;i++)scanf("%lf %lf",&x[i],&y[i]);sort(y+1,y+n+1,cmp);sort(x+1,x+n+1,cmp);a[1]=x[2]-x[1];a[n]=x[n]-x[n-1];for(i=3;i<=n;i++)a[i-1]=x[i]-x[i-2];sort(a+1,a+n+1,cmp);double ans=0;for(i=1;i<=n;i++)ans+=y[i]*a[i];printf("%.1fn",ans/2);}}
