Problem: Professor Abacus has just built a new computing engine for making numerical tables. It was designed to calculate the values of a polynomial function in one variable at several points at a time. With the polynomial function f(x) = x2 + 2x + 1, for instance, a possible expected calculation result is 1 (= f(0)), 4 (= f(1)), 9 (= f(2)), 16 (= f(3)), and 25 (= f(4)).

It is a pity, however, the engine seemingly has faulty components and exactly one value among those calculated simultaneously is always wrong. With the same polynomial function as above, it can, for instance, output 1, 4, 12, 16, and 25 instead of 1, 4, 9, 16, and 25.

You are requested to help the professor identify the faulty components. As the first step, you should write a program that scans calculation results of the engine and finds the wrong values.



Input

The input is a sequence of datasets, each representing a calculation result in the following format.

d
v0
v1
...
vd+2


Here, d in the first line is a positive integer that represents the degree of the polynomial, namely, the highest exponent of the variable. For instance, the degree of 4x5 + 3x + 0.5 is five and that of 2.4x + 3.8 is one. d is at most five.

The following d + 3 lines contain the calculation result of f(0), f(1), ... , and f(d + 2) in this order, where f is the polynomial function. Each of the lines contains a decimal fraction between -100.0 and 100.0, exclusive.

You can assume that the wrong value, which is exactly one of f(0), f(1), ... , and f(d+2), has an error greater than 1.0. Since rounding errors are inevitable, the other values may also have errors but they are small and never exceed 10-6.

The end of the input is indicated by a line containing a zero.

Output

For each dataset, output i in a line when vi is wrong.

Example

Input

2
1.0
4.0
12.0
16.0
25.0
1
-30.5893962764
5.76397083962
39.3853798058
74.3727663177
4
42.4715310246
79.5420238202
28.0282396675
-30.3627807522
-49.8363481393
-25.5101480106
7.58575761381
5
-21.9161699038
-48.469304271
-24.3188578417
-2.35085940324
-9.70239202086
-47.2709510623
-93.5066246072
-82.5073836498
0


Output

2
1
1
6

Solution (in JAVA):

Solution:
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;

public class Main {
	public static double EPS = 1E-9;
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while(true) {
			int d = sc.nextInt();
			if (d == 0) {
				break;
			}
			ArrayList<Pair> errors = new ArrayList<Pair>();
			double[] v = new double[d+3];
			for(int i=0;i<d+3;i++) {
				v[i] = sc.nextDouble();
			}
			for(int i=0;i<(1<<d+3);i++) {
				if (Integer.bitCount(i) != d+1) {
					continue;
				}
				double[][] a = new double[d+1][d+1];
				double[] b = new double[d+1];
				int i_ = 0;
				for(int x=0;x<d+3;x++) {
					if ((i&(1<<x)) == 0) {
						continue;
					}
					for(int j=0;j<=d;j++) {
						a[i_][j] = Math.pow(x, j);
					}
					b[i_] = v[x];
					i_++;
				}
				double[] c = Matrix.solveEquation(a, b);

				ArrayList<Double> err = new ArrayList<Double>();
				ArrayList<Integer> errI = new ArrayList<Integer>();
				for(int x=0;x<d+3;x++) {
					if ((i&(1<<x)) != 0) {
						continue;
					}
					double y = 0;
					for(int j=0;j<=d;j++) {
						y += c[j] * Math.pow(x, j);
					}
					double error = Math.abs(y - v[x]);
					err.add(error);
					errI.add(x);
				}
				if (err.get(0) < err.get(1)) {
					errors.add(new Pair(err.get(0),errI.get(0),err.get(1),errI.get(1)));
				}else{
					errors.add(new Pair(err.get(1),errI.get(1),err.get(0),errI.get(0)));
				}
			}
			Collections.sort(errors,new Comparator<Pair>() {
				public int compare(Pair o1, Pair o2) {
					return o1.s < o2.s ? -1 : (o1.s == o2.s ? 0 : 1);
				}
			});
			for(Pair x:errors) {
				//System.out.println(x.s + " " + x.l);
				if (x.l >= 1 - 1E-4) {
					System.out.println(x.li);
					break;
				}
			}
		}
	}

}

class Pair {
	double s,l;
	int si,li;
	public Pair(double s,int si,double l,int li) {
		this.s = s;
		this.l = l;
		this.si = si;
		this.li = li;
	}
}

class Matrix {
	public static final double EPS = 1E-8;
	public static double[][] add(double[][] a,double[][] b) {
		int n = a.length;
		int m = a[0].length;
		double[][] c = new double[n][m];
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				c[i][j] = a[i][j] + b[i][j];
			}
		}
		return c;
	}
	public static double[][] muliply(double[][] a,double k) {
		int n = a.length;
		int m = a[0].length;
		double[][] c = new double[n][m];
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				c[i][j] = a[i][j] * k;
			}
		}
		return c;
	}
	public static double[][] muliply(double[][] a,double[][] b) {
		int n = a.length;
		int m = b[0].length;
		double[][] c = new double[n][m];
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				for(int k=0;k<n;k++) {
					c[i][j] += a[i][k] * b[k][j];
				}
			}
		}
		return c;
	}
	//disruptive
	public static double[] solveEquation(double[][] A,double[] b) {
		int n = A.length;
		double[][] B = new double[n][n+1];
		for(int i=0;i<n;i++) {
			for(int j=0;j<n;j++) {
				B[i][j] = A[i][j];
			}
			B[i][n] = b[i];
		}
		for(int i=0;i<n;i++) {
			int pivot = i;
			for(int j=i;j<n;j++) {
				if (Math.abs(B[j][i]) > Math.abs(B[pivot][i])) {
					pivot = j;
				}

			}
			swapRow(B, i, pivot);
			if (Math.abs(B[i][i]) < EPS) {
				return null;
			}
			for(int j=i+1;j<=n;j++) {
				B[i][j] /= B[i][i];
			}
			for(int j=0;j<n;j++) {
				if (i==j) {
					continue;
				}
				for(int k=i+1;k<=n;k++) {
					B[j][k] -= B[j][i] * B[i][k];
				}
			}
		}
		double[] x = new double[n];
		for(int i=0;i<n;i++) {
			x[i] = B[i][n];
		}
		return x;
	}
	public static void swapRow(double[][] A,int i,int j) {
		double[] temp = A[i];
		A[i] = A[j];
		A[j] = temp;
	}
}