#include<stdio.h>
#include<math.h>

void run(void){
  int a,b;
  scanf("%d%d",&a,&b);
  if(a==b){
    printf("%.6lf\n",sqrt(2)*a);
  } else {
    double t=fabs(a-b);
    printf("%.6lf\n",sqrt(t*(a+b)));
  }
  return;
}

int main(void){
  run();
  return 0;
}