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

void main(void)
{
int n;  //no data points
float x[10], y[10];
float xx,sum=0,prod=1;
clrscr();
do	{    //DO WHILE LOOP
	printf("\nEnter the no. of data points --> ");
	scanf("%d",&n);
	}  while(n>10 || n<0);

for(int ct=0;ct<n;ct++)
	{
	printf("Enter the values of x%d & corresponding"
						" y%d --> ",ct+1,ct+1);
	scanf("%f%f",&x[ct],&y[ct]);
	}
printf("Enter the value at which f(x) is desired --> ");
scanf("%f",&xx);
printf("\n");
for(int i=0;i<n;i++)
	{
	for(int j=0;j<n;j++)
		{
		if(i==j)  continue;
		prod*=((xx-x[j])/(x[i]-x[j]));
		}
	sum+=prod*y[i];
	prod=1;
	printf("estimating....  %f\n",sum);
	}
printf("\n\nThe reqd. value of f(x) at %f is %f",xx,sum);
while(!kbhit());   //do nothing loop, eqv. to getch();
}