#include <iostream>

int BinSearch(const int* arr, int amount) {
  int mid = 0, end = 0;
  int begin = 0, mid_index = 0;
  end = amount - 1;
  while (end - begin >= 1) {
    if (arr[begin] < arr[end]) {
      return begin;
    }
    mid = arr[(begin + end) / 2];
    mid_index = (begin + end) / 2;
    if (mid_index == 0) {
      return end;
    }
    if (mid < arr[mid_index - 1] && mid < arr[mid_index + 1]) {
      return mid_index;
    }
    if (mid > arr[mid_index - 1] && mid > arr[mid_index + 1]) {
      return mid_index + 1;
    }
    if (mid < arr[end] && mid_index > 0) {
      end = mid_index - 1;
    } else if (mid > arr[begin]) {
      begin = mid_index + 1;
    } else {
      return 0;
    }
  }
  return 0;
}
void FindShift() {
  int amount = 0;
  std::cin >> amount;
  int* arr = new int[amount];
  for (int i = 0; i < amount; i++) {
    std::cin >> arr[i];
  }
  std::cout << BinSearch(arr, amount);
  delete[] arr;
}
int main() {
  FindShift();
  return 0;
}