#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    int len = 0;
    for (int i = 0; i < n; i++) {
        int temp = 1;
        int pre = a[i];
        for (int j = i + 1; j < n; j++) {
            if (a[j] == pre + 1) {
                temp++;
                pre = a[j];
            }
            len = max(len, temp);
        }
    }
    cout << n - len << endl;
    return 0;
}