#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 998244353;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
typedef complex<ld> Point;
const ld eps = 1e-3;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
typedef pair<ld, ld> LDP;

typedef vector<ld> vec;
typedef vector<vec> mat;
void debag_matrix(const mat &A) {
	rep(i, A.size()) {
		rep(j, A[i].size()){
			cout << A[i][j] << " ";
	    }
		cout << endl;
	}
}
void gauss_hakidasi(mat &A) {
	int n = A.size(), m = A[0].size();
	int t = min(n, m);
	rep(k, t) {
		int chk = -1;
		Rep(i,k, n) {
			if (abs(A[i][k]) > eps) {
				chk = i; break;
			}
		}
		if (chk < 0)return;
		swap(A[k], A[chk]);
		ld x = A[k][k];
		rep(i, m) {
			A[k][i] /= x;
		}
		rep(i, n) {
			if (i == k)continue;
			x = A[i][k];
			rep(j, m) {
				A[i][j] -= x * A[k][j];
			}
		}
	}
}
int n;
ld d[10];

bool valid(int id, mat A) {
	gauss_hakidasi(A);
	//debag_matrix(A);
	ld sum = 0;
	ld cur = 1;
	per(i, n + 1) {
		sum += A[i][n+1] * cur; cur *= id;
	}
	return abs(sum - d[id]) < eps;
}
int main() {
	while (cin >> n, n) {
		rep(i, n + 3)cin >> d[i];
		rep(i, n + 3) {
			mat A; int ck = 0;
			per(j, n + 3) {
				if (i == j)continue;
				vector<ld> v;
				ld cur = 1;
				rep(k, n + 1) {
					v.push_back(cur);
					cur *= j;
				}
				reverse(v.begin(), v.end());
				v.push_back(d[j]);
				if (A.size() < n + 1)A.push_back(v);
				else ck = j;
			}
			//debag_matrix(A);
			//cout << ck << endl;
			if (valid(ck, A)) {
				cout << i << endl; break;
			}

		}
		//cout << "finish" << endl;
	}
	//stop
	return 0;
}

