Bisection Method Program. Just one issue I have

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

double f(double x)
{
return 3*(x+1)*(x-.5)*(x-1);  //change equation for each problem
}

int main()
{
    double a, b, p, Tol, FA, FP;
    int i=1;
    int No;

    printf("Enter first endpoint: ");
    scanf ("%lf", &a);

    printf("Enter second/last endpoint: ");
    scanf ("%lf", &b);

    printf("Desired Tolerance: ");
    scanf ("%lf", &Tol);

    printf("Maximum Iterations: ");
    scanf ("%d", &No);
    FA = f(a);

    while (i<=No)
    {
        p=a+(b-a)/2;
        FP = f(p);

        if ((FP==0)||((b-a)/2)< Tol)
        {
            printf("%lf\n",p);
            break;
        }
        i++;  //i=i+1

        if ((FA*FP)>0)
        {
            a=p;
            FA=FP;
        }
           else
           {
                b=p;
           }
        }
   if (i>No)
   {
   printf("Method Failed after %d", No);
   printf(" iterations");
   }
}