polynomial gap thing

#include <stdio.h>
#include <stdlib.h>

int main()								//please take note, this is not the full version. i cannot understand the f_left/f_right parts
{										//so i just left it as is first. the upper parts should be all inside
    printf("Hello world!\n");

    float stepsize;                     //should be the subinterval gap
    int p,q,r,s;                        //to replace a0,a1,a2,a3 because it is conflicitng with the end points
    float endpointax,endpointbx;
    float ay,by;

    int k=0;
    float L,M;

    int n;

    printf("the cubic polynomial has the form of 'f(X)=(a0)x^3 + (a1)x^2 +(a2)x + (a3)'\n\n");
    printf("what is the value of a0?\t");
    scanf("%d",&p);
    printf("what is the value of a1?\t");
    scanf("%d",&q);
    printf("what is the value of a2?\t");
    scanf("%d",&r);
    printf("what is the value of a3?\t");
    scanf("%d",&s);

    printf("\n\nWhat is the x value of interval endpoint A?\t");
    scanf("%f",&endpointax);
    printf("What is the x value of interval endpoint B?\t");
    scanf("%f",&endpointbx);

    printf("\nWhat is the step size?\t");
    scanf("%f",&stepsize);

    n=(endpointbx-endpointax)/stepsize;         //to find number of subintervals

    ay= p* endpointax*endpointax*endpointax + q* endpointax*endpointax + r*endpointax + s;
    by= p* endpointbx*endpointbx*endpointbx + q* endpointbx*endpointbx + r*endpointbx + s;
    printf("\nA= %.2f,%.2f and B=%.2f,%.2f\n\n",endpointax,ay,endpointbx,by);

    while(k<=n-1)
    {
        L=endpointax + k*stepsize;
        M=L+stepsize;
        ay= p* L*L*L + q* L*L + r*L + s;
        by= p* M*M*M + q* M*M + r*M + s;
        /*
        check_roots(ay,by,endpointbx+k);*/
        printf("The %dth interval is %.2f,%.2f to %.2f,%.2f\n",k+1,L,ay,M,by);


        k++;
    }



    return 0;
}