#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <set>
#include <map>

using namespace std;

map<long long, long long> m;

int main()
{
	int n;
	cin >> n;
	vector<long long> v(n);
	for (int i = 0; i < n; ++i)
	{
		cin >> v[i];
	}

	for (int i = 0; i < n; ++i)
	{
		long long time = 0;
		while (v[i] < 1000)
		{
			time += (1000 - v[i]);
			if (m[time] != 0 && m[time] != i + 1)
			{
				m[time] = -228;
			}
			else
			{
				m[time] = i + 1;
			}
			++v[i];
		}
		m[time] = -i - 1;
	}

	long long pr = 0;
	bool f = false;
	for (int t = 1; t < 1e8; ++t)
	{
		if (m[t] == -228)
		{
			cout << t;
			return 0;
		}

		if (m[t] != 0)
		{
			if (m[t] < 0)
			{
				if ((abs(abs(m[t]) - m[pr])) > abs(t - pr))
				{
					cout << t;
					return 0;
				}
				f = true;
			}
			else if (f && m[t] != m[pr])
			{
				cout << t;
				return 0;
			}
			else if (!f && abs(m[t] - m[pr]) > abs(t - pr))
			{
				cout << t;
				return 0;
			}
			pr = t;
		}
	}
}