#include<stdio.h>
#include<conio.h>
#include<math.h>

int n,choice, i;
float x0, y0, h, y1, x1, x0, z0,sum, temp, k1,k2,k3,k4;
float l1,l2,l3,l4;

float f ( float, float, float);
float g(float p, float q, float r);

void main()
{

	printf("Enter starting value of x and corr. val of y and z.\n");
	scanf("%f%f%f", &x0, &y0, &z0);

	printf("Enter value of x for which y is found \n");
	scanf("%f", &x1);

	h = x1-x0;

	k1 = h * f ( x0, y0, z0);

	l1 = h * g ( x0, y0, z0);
	k2 = h * f(x0 + h/2, y0 + k1/2, z0+ l1/2);

	l2 = h * g(x0 + h/2, y0 + k1/2, z0+ l1/2);
	k3 = h * f(x0 + h/2, y0 + k2/2, z0+l2/2);

	l3 = h * g(x0 + h/2, y0 + k2/2, z0+l2/2);
	k4 = h * f (x0+h , y0+k3, z0+ l3);
	l4 = h * g (x0+h , y0+k3, z0+l3);

	y1 = y0 + (k1+2*k2+2*k3+k4)/6;


	printf("y = %f", y1);

	getch();


}

float f(float p, float q, float r)
{
	return(r);

}

float g(float p, float q, float r)
{
	return(p*r*r - q*q);

}