#include <bits/stdc++.h> using namespace std; class CPoint{ public: int x,y; CPoint(int x,int y){ this->x=x; this->y=y; } }; double operator-(CPoint&a,CPoint&b){ return sqrt(pow(a.x-b.x,2)+pow(a.y-b.y,2)); } int main() { int n; cin>>n; for(int i=0;i<n;++i){ int a,b,c,d; cin>>a>>b>>c>>d; CPoint A(a,b),B(c,d); printf("%.2f\n",A-B); } } // 64 位输出请用 printf("%lld")