#include<iostream>
#include<math.h>
using namespace std;
int main( int argc, char * argv[] )
{
  float a,b,c,p,q,z;
  cout<<"請依序輸入ax2+bx+c=0之a,b,c"<<endl;
  cout<<"a=";             // 輸入a
  cin>>a;
  cout<<"b=";             //輸入b
  cin>>b;
  cout<<"c=";             //輸入c
  cin>>c;

  if(a==0)
  {
    if(b==0){
              if(c==0)
                cout<<"x有無限多解";
              else
                cout<<"輸入錯誤";
            }
    else{
              q=-c/b;
              cout<<"x="<<q;
        }
  }
  else
  {             z=sqrt(b*b-4*a*c);
              if(b*b-4*a*c>=0){
                p=(-b+z)/2/a;
                q=(-b-z)/2/a;
                cout<<"x="<<p<<","<<q;
                              }
              else
                cout<<"There are no real roots.";
  }

  return 0;
}