Lagrange Interpolation

#include<iostream>
#include<conio.h>
#include<stdlib.h>

using namespace std;

int main(){
    float x[30], y[30],X, p, sum=0;
    int n;

    cout<<"Enter the no of data you want to input: ";
    cin>>n;

    for(int i=0;i<n;i++) {
        cout<<"X ["<<i+1<<"] :";
        cin>>x[i];
        cout<<"Y ["<<i+1<<"] :";
        cin>>y[i];
    }

    cout<<"Enter the value for x: ";
    cin>>X;

    for(int i=0;i<n;i++){
        p=1;
        for(int j=0;j<n;j++){
            if (i != j){
                p=p*((X-x[j])/(x[i]-x[j]));
            }
        }
        sum=sum+(p*y[i]);
    }
    cout<<endl<<"The root is: "<<sum;
    getch();
}