#include <iostream>#include <stdio.h>#include <algorithm>#include <queue>#include <map>#include <set>#include <vector>#include <cstring>#include <math.h>using namespace std;const double eps = 1e-4;double r1, r2;double f(double x){return 8. * sqrt((r1*r1 - x*x) * (r2*r2 - x*x));}double simpson(double a, double b){int n, k;double h, t1, t2, s1, s2, ep, p, x;n = 1, h = b - a;t1 = h * ( f(a) + f(b) ) / 2.;s1 = t1;ep = eps + 1.;while(ep >= eps){p = 0;for(k = 0; k <= n-1; k++){x = a + (k + 0.5) * h;p += f(x);}t2 = (t1 + h * p) / 2.;s2 = (4. * t2 - t1) / 3.; ep = fabs(s2 - s1);t1 = t2, s1 = s2, n += n, h /= 2.;}return s2;}int main(){int CASE;cin >> CASE;while(CASE--){scanf("%lf%lf", &r1, &r2);if(r2 < r1)swap(r1, r2);double t = simpson(0., r1);printf("%.4lfn", t);}return 0;}
