how to solve quadratic equation

#include<stdio.h>
#include<math.h>
main()
{
int a,b,c;
float r1,r2,re,im,p,q,x,y;
printf("enter the coeficiants of ur quadratic equation\n  ");
scanf("%d %d %d",&a,&b,&c);
if(a==0)
printf("this is not a quadratic equation");
else
{
p=b*b-4*a*c;
if(p==0)
{
printf("there is only one root\n");
r1=-b/(2.0*a);
printf("\tthe root is =%f",r1);
}
if(p<0)
{
q=-p;
re=sqrt(q)/(2*a);
im=-b/(2.0*a);
printf("\tthe roots are imaginary\n");
printf("\troot 1= %f +i %f\n",re,im);
printf("\troot 2=%f -i %f",re,im);
}
if(p>0)
{
x=(-b+sqrt(p))/(2*a);
y=(-b-sqrt(p))/(2*a);
printf("\nroot 1=%f",x);
printf("\nroot 2=%f",y);
}
}
}