#include <bits/stdc++.h>
#define debug cerr << "[" << __LINE__ << "] "
#define SZ(x) (int) x.size() - 1
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> inline void chkmax(T& x, T y) { x = max(x, y); }
template <typename T> inline void chkmin(T& x, T y) { x = min(x, y); }
template <typename T> inline void read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;
	for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);
	x *= f;
}
const int N = 25;
int n, a[N], lg[1 << 23], f[1 << 23];//, pp[1 << 23];
ll sum[1 << 23];
vector <int> t[25];
signed main() {
	read(n);
	F(i, 1, n) {
		read(a[i]);
		// cout << a[i] << endl;
	}
	DF(i, n, 1) a[i] -= a[i - 1];
	int full = (1 << n) - 1;
	F(i, 1, n) lg[1 << (i - 1)] = i;
	F(i, 1, full) {
		int lb = i & -i;
		sum[i] = sum[i ^ lb] + a[lg[lb]];
		F(j, 1, n) {
			if (i & (1 << (j - 1))) {
				chkmax(f[i], f[i ^ (1 << (j - 1))]);
			}
		}
		if (!sum[i]) f[i]++;
	}
	cout << n - f[full];
	// F(i, 1, (1 << n) - 1) {
	// 	pp[i] = pp[i ^ lb] + 1;
	// 	if (!sum[i]) t[pp[i]].push_back(i);
	// }
	return 0;
}