#include<stdio.h>
#include<math.h>
int main()
{
    double a,b,c,disc,x1,x2,p,q;
    printf("please input: a,b,c\n");
    scanf("a=%lf,b=%lf,c=%lf",&a,&b,&c);
    disc=b*b-4*a*c;
    if(disc<0)
    printf("This equation hasn't real roots\n");
    else 
    {
        p=-b/(2.0*a);
        q=sqrt(disc)/(2.0*a);
        x1=p+q;x2=p-q;
        printf("real roots:\nx1=%7.2f\nx2=%7.2f\n",x1,x2);
        }
}