#include <stdio.h>

 #include <string.h>

 #include <stdlib.h>

 #include <math.h>

 double a,b,c,x,y;

 double scla(double xx)

 {

     double yy;

     yy = a*xx*xx+b*xx+c;

     return sqrt((xx-x)*(xx-x) + (yy-y)*(yy-y));

 }

 double thfind(double left,double right)

 {

     double midmid,mid;

     while(left + 1e- < right)

     {

         mid = (left + right)/;

         midmid = (mid+right)/;

         if(scla(mid) < scla(midmid))

             right = midmid;

         else

             left = mid;

     }

     return scla(left);

 }

 int main(void)

 {

     scanf("%lf %lf %lf %lf %lf",&a,&b,&c,&x,&y);

     printf("%.3lf\n",thfind(-,));

     return ;

 }