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 CPP):

Solution:
#include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
template<class T>
using Table = vector<vector<T>>;
const ld eps=1e-9;

//// < "D:\D_Download\Visual Studio 2015\Projects\programing_contest_c++\Debug\a.txt"

/* verified AOJ1327 One-Dimensional Cellular Automaton
~Matrix~
??????????°????????¨?????????§??????
vector iostream cmath cassert ??????
Matrix a(VV), b(VV);
?????????:a*b
????????????:l*a
???:a+b
???:a-b
??¢???:a.transport()
?????????:a.cofactor()
?????????:a.det()
a???i???j??????:a.get(i,j)???
a???i??????j?????????k?????£??\:set(i,j,k)
????????????a[i][j] (a[i][j]=k)
a???x???:a.pow(x)
n*n?????¬??????E:Matrix(n)
m*n 0??????:Matrix(m,n)
m*n ??¨????´????p?????????:Matrix(m,n,p)
Row???row??§????????????(m*1??????):Matrix(row)
**(??´??°??????)**
????§????:a.triangulate()
?????????:a.rank()
?????????:a.inverse()
//(????????????a.det()?????????a.pre_inverse()??§?±??????? ??´??°???)
??¬??????????¶???????:a.rowReduction()
//??£???????¬?????¨????????§£??????
***
*/

#include <vector>
#include <iostream>
#include <cmath>
#include <cassert>
using namespace std;

typedef ld Elem;
typedef vector<Elem> Row;
typedef vector<Row> VV;

typedef long double ld;
const ld EPS = 1e-11;

const bool isZero(const Elem e) {
	return abs(e) < EPS;
}

struct Matrix {
	VV matrix;
	int n, m;

	Matrix(const VV &matrix_);
	explicit Matrix(int n_);
	explicit Matrix(const Row &row);
	Matrix(int m_, int n_);
	Matrix(int m_, int n_, Elem e);

	const Elem get(const int i, const int j) const;
	void set(const int x, const int y, const Elem k);

	const Matrix operator + (const Matrix &rhs) const;
	const Matrix operator * (const Matrix &rhs) const;
	const Matrix operator - (const Matrix &rhs) const;
	Matrix &operator += (const Matrix &rhs);
	Matrix &operator *= (const Matrix &rhs);
	Matrix &operator -= (const Matrix &rhs);

	Row &operator[](const int x);

	const Matrix transport() const;
	const Matrix pow(int x) const;
	const Matrix cofactor(int x, int y) const;
	const Elem det() const;

	const Matrix triangulate() const;
	const int rank() const;

	//?????????????????¨????????°???(?????????)*(?????????)?????????
	//A:matrix,return det A * A^-1
	const Matrix pre_inverse() const;
	const Matrix inverse() const;
	const Matrix rowReduction() const;
};

const Matrix operator * (const Elem lambda, const Matrix &rhs) {
	Matrix tmp(rhs);
	for (int i = 0; i < rhs.m; i++)
		for (int j = 0; j < rhs.n; j++)
			tmp.set(i, j, tmp.get(i, j) * lambda);
	return tmp;
}

Matrix::Matrix(const VV &matrix_) : matrix(matrix_) {
	m = matrix_.size();
	if (m == 0) n = 0;
	else n = matrix_[0].size();
}
Matrix::Matrix(int n_) : m(n_), n(n_) {
	matrix = VV(n, Row(n, 0));
	for (int i = 0; i < n; ++i)
		set(i, i, 1);
}
Matrix::Matrix(const Row &row) : m(1), n(row.size()), matrix(VV(1, row)) {
	//size???m???vector<Elem>??????mx1???????????????
	(*this) = transport();
}
Matrix::Matrix(int m_, int n_) : m(m_), n(n_) {
	matrix = VV(m, Row(n, 0));
}
Matrix::Matrix(int m_, int n_, Elem e) : m(m_), n(n_) {
	matrix = VV(m, Row(n, e));
}

const Elem Matrix::get(const int i, const int j) const {
	if (0 <= i && i < m && 0 <= j && j < n)
		return matrix[i][j];

	cerr << "get(" << i << "," << j << ")is not exist." << endl;
	throw;
}
void Matrix::set(const int i, const int j, const Elem k) {
	if (0 <= i && i < m && 0 <= j && j < n) {
		*(matrix[i].begin() + j) = k;
		return;
	}
	cerr << "set(" << i << "," << j << ")is not exist." << endl;
	throw;
}

const Matrix Matrix::operator + (const Matrix &rhs) const {
	assert(m == rhs.m && n == rhs.n);

	Matrix tmp(m, n, 0);
	for (int i = 0; i < m; i++) {
		for (int j = 0; j < n; j++) {
			tmp.set(i, j, get(i, j) + rhs.get(i, j));
		}
	}
	return tmp;
}

const Matrix Matrix::operator * (const Matrix &rhs) const {
	assert(n == rhs.m);

	Matrix tmp(m, rhs.n, 0);
	Elem sum;
	for (int i = 0; i < m; i++)
		for (int j = 0; j < rhs.n; j++) {
			sum = 0;
			for (int k = 0; k < n; k++) {
				sum += get(i, k) * rhs.get(k, j);
			}
			tmp.set(i, j, sum);
		}
	return tmp;
}

const Matrix Matrix::operator - (const Matrix &rhs) const {
	return *this + ((Elem)-1 * rhs);
}

Matrix &Matrix::operator += (const Matrix &rhs) {
	return *this = *this + rhs;
}

Matrix &Matrix::operator *= (const Matrix &rhs) {
	return *this = *this * rhs;;
}

Matrix &Matrix::operator -= (const Matrix &rhs) {
	return *this = *this - rhs;
}

Row &Matrix::operator[](const int x) {
	return matrix[x];
}

const Matrix Matrix::transport() const {
	VV tmp;
	for (int i = 0; i < n; i++) {
		Row row;
		for (int j = 0; j < m; j++)
			row.push_back(get(j, i));
		tmp.push_back(row);
	}
	return tmp;
}

const Matrix Matrix::pow(int x) const {
	Matrix tmp(*this), e(m);
	for (int i = 1; i <= x; i <<= 1) {
		if ((x & i) > 0)
			e = e * tmp;
		tmp = tmp * tmp;
	}
	return e;
}

const Matrix Matrix::cofactor(int x, int y) const {
	VV tmp;
	for (int i = 0; i < m; i++) {
		if (x == i) continue;
		Row row;
		for (int j = 0; j < n; j++) {
			if (y == j) continue;
			row.push_back(get(i, j));
		}
		tmp.push_back(row);
	}
	return Matrix(tmp);
}

const Elem Matrix::det() const {
	assert(n == m);

	if (m == 1)
		return get(0, 0);
	Elem sum = 0;
	for (int i = 0; i < m; i++) {
		sum += ((i % 2 == 0 ? 1 : -1) * get(i, 0)) * Matrix(cofactor(i, 0)).det();
	}
	return sum;
}

const Matrix Matrix::triangulate() const {
	Matrix tmp(*this);
	Elem e;
	int p = 0;
	for (int i = 0; i < m && p < n; i++, p++) {
		if (isZero(tmp.get(i, p))) {
			tmp.set(i, p, 0);
			bool flag = true;
			for (int j = i + 1; j < m; j++)
				if (!isZero(tmp.get(j, p))) {
					for (int k = 0; k < n; k++)
						tmp.set(i, k, tmp.get(i, k) + tmp.get(j, k));
					//tmp[i].swap(tmp[j]);
					flag = false;
					break;
				}
			if (flag) {
				i--;
				continue;
			}
		}
		for (int j = i + 1; j < m; j++) {
			e = tmp.get(j, p) / tmp.get(i, p);
			for (int k = 0; k < n; k++)
				tmp.set(j, k, tmp.get(j, k) - tmp.get(i, k) * e);
		}
	}
	return tmp;
}

const int Matrix::rank() const {
	Matrix tmp(triangulate());
	for (int i = min(tmp.m - 1, tmp.n - 1); i >= 0; i--) {
		for (int j = tmp.n - 1; j >= i; j--)
			if (isZero(tmp.get(i, j)))
				continue;
			else
				return i + 1;
	}
	return 0;
}

const Matrix Matrix::pre_inverse() const {
	assert(m == n);

	Matrix tmp(m, n, 0);
	for (int i = 0; i < m; i++)
		for (int j = 0; j < n; j++)
			tmp.set(i, j, ((i + j) % 2 == 0 ? 1 : -1)*cofactor(i, j).det());
	return tmp.transport();
}

/*O(n!)????£?
const Matrix Matrix::inverse() const {
Matrix tmp(pre_inverse());
Elem e = det();
assert(!isZero(e));
tmp = 1 / e * tmp;
return tmp.transport();
}*/

const Matrix Matrix::inverse() const {
	assert(m == n);

	Matrix tmp(m, n * 2), tmp2(m, n);
	for (int i = 0; i < m; i++)
		for (int j = 0; j < n; j++)
			tmp.set(i, j, get(i, j));
	for (int i = 0; i < m; i++)
		tmp.set(i, i + n, 1);

	tmp = tmp.rowReduction();

	//?????????????????¨??????????????????????????§??????
	for (int i = 0; i < m; i++)
		assert(isZero(tmp.get(i, i) - 1));

	for (int i = 0; i < m; i++)
		for (int j = 0; j < n; j++)
			tmp2.set(i, j, tmp.get(i, j + n));

	return tmp2;
}

/*
a b c j
d e f k
g h i l

ax+by+cz=j;
dx+ey+fz=k;
gx+hy+iz=l;

|
V

1 0 0 x
0 1 0 y
0 0 1 z
???????????????
*/
const Matrix Matrix::rowReduction() const {
	Matrix tmp(*this);
	Elem e;
	int p = 0;
	for (int i = 0; i < m && p < n; i++, p++) {
		if (isZero(tmp.get(i, p))) {
			tmp.set(i, p, 0);
			bool flag = true;
			for (int j = i + 1; j < m; j++)
				if (!isZero(tmp.get(j, p))) {
					for (int k = 0; k < n; k++)
						tmp.set(i, k, tmp.get(i, k) + tmp.get(j, k));
					//tmp[i].swap(tmp[j]);
					flag = false;
					break;
				}
			if (flag) {
				i--;
				continue;
			}
		}
		e = 1 / tmp.get(i, p);
		tmp.set(i, p, 1);
		for (int k = i + 1; k < n; k++)
			tmp.set(i, k, tmp.get(i, k)*e);
		for (int j = 0; j < m; j++) {
			if (i == j) continue;
			e = tmp.get(j, p);
			for (int k = 0; k < n; k++)
				tmp.set(j, k, tmp.get(j, k) - tmp.get(i, k) * e);
		}
	}
	return tmp;
}
long long int powint(long long int a, long long int b) {
	assert(b >= 0);
	if (b == 0)return 1;
	if (b == 1)return a;
	long long int ans = 1;
	long long int aa = powint(a, b / 2);
	ans *= aa*aa;
	if (b % 2)ans *= a;
	return ans;
}
int main() {
	while (1) {
		int d; cin >> d;
		if (!d)break;
		vector<Elem>as;
		vector<vector<Elem>>vs;
		for (int i = 0; i < d + 3; ++i) {
			Elem a; cin >> a;
			as.push_back(a);
			vector<Elem>v;
			for (int j = 0; j <= d; ++j) {
				v.push_back(powint(i, j));
			}
			v.push_back(a);
			vs.push_back(v);
		}
		vector<int>nums(d + 3);
		for (int i = 0; i < d + 3; ++i) {
			for (int j = i + 1; j < d + 3; ++j) {
				VV mat;
				for (int k = 0; k < d + 3; ++k) {
					if (i == k || j == k)continue;
					mat.push_back(vs[k]);
				}
				Matrix matrix(mat);
				matrix = matrix.rowReduction();
				vector<ld>xs;
				for (int k = 0; k <= d; ++k) {
					xs.push_back(matrix[k][d + 1]);
				}
				ld idis, jdis;
				{
					ld num = 0;
					for (int k = 0; k <= d; ++k) {
						num += vs[j][k] * xs[k];
					}
					jdis = abs(num - vs[j][d + 1]);
					if (jdis < 1e-1)nums[j]++;
				}
				{
					ld num = 0;
					for (int k = 0; k <= d; ++k) {
						num += vs[i][k] * xs[k];
					}
					idis = abs(num - vs[i][d + 1]);
					if (idis < 1e-1)nums[i]++;
				}
			}
		}
		int ans = min_element(nums.begin(), nums.end()) - nums.begin();
		cout << ans << endl;
	}
	
	return 0;
}