The varriable is being used without being defined

#include <iostream>
#include <math.h>
using namespace std;
void main()
{
 
int x,y,p,q,a,b,c,d;
double A,B,D,x1,x2,x3,y1,y2,y3,f,i;
cin>>a;
cin>>b;
cin>>c;
cin>>d;
f=3;
p=(-1/3)*((b/a)*(b/a))+(c/a);
q=(2/27)*((b/a)*(b/a)*(b/a))-(b*c/3*(a*a))+(d/a);
D=pow((p/3),3)+pow((p/2),2);
A=pow((-q/2)+sqrt(D),1/3);
B=pow((-q/2)-sqrt(D),1/3);
x1=(A+B)-(b/(3*a));
x2=((-1/2)*(a+b)+i*(sqrt(f)/2)*(a-b))-(b/(3*a));
x3=((-1/2)*(a+b)-i*(sqrt(f)/2)*(a-b))-(b/(3*a));
cout<<"x1:"<<x1<<"\n";
cout<<"x2:"<<x2<<"\n";
cout<<"x3:"<<x3<<"\n";
}

x2_real = ((-1/2)*(a+b)-(b/(3*a);
x2_imaginary = (sqrt(f)/2)*(a-b);
x3_real = ((-1/2)*(a+b)-(b/(3*a);
x3_imaginary = -(sqrt(f)/2)*(a-b);

x3_real = x2_real;
x3_imaginary = -x2_imaginary;

[CPP]#include <iostream>
#include <math.h>
#include <complex>
using namespace std;
void main()
{
float x,y,a,b,c,d,q,g,h,p,x1,x2_real,x2_imaginary,x3_real,x3_imaginary,y1,y2,y3,f;
double j,k,A,B,D;
cin>>a;
cin>>b;
cin>>c;
cin>>d;;
f=3;
p=((b/a)*(b/a))/(-3)+(c/a);
cout<<"p:"<<p<<"\n";
q=((2*((b/a)*(b/a)*(b/a)))/27)-(b*c/3*(a*a))+(d/a);
cout<<"q:"<<q<<"\n";
g=p/3;
h=q/2;
D=(g*g*g)+(h*h);
cout<<"D:"<<D<<"\n";
j=(-q/2)+(sqrt(D));
A=pow(j,1./3.);
cout<<"A:"<<A<<"\n";
k=((-q/2)-sqrt(D));
cout<<"k:"<<k<<"\n";
B=pow(k,1./3.);
cout<<"B:"<<B<<"\n";
x1=(A+B)-(b/(3*a));
x2_real = ((A+B)/(-2)-(b/(3*a)));
x2_imaginary = (sqrt(f)/2)*(A-B);
x3_real = ((A+B)/(-2)-(b/(3*a)));
x3_imaginary = -(sqrt(f)/2)*(A-B);
cout<<"x1:"<<x1<<"\n";
cout<<"x2:"<<x2_real<<" "<<x2_imaginary<<"\n";
cout<<"x3:"<<x3_real<<" "<<x3_imaginary<<"\n";
}

B=-pow(abs(k),1./3.);//if(k < 0)