#include <iostream>
//binary_search function
int binary_search(int a[], int l, int r, int key) {
    while (l <= r) {
          int m = l + (r - l) / 2;
          if (key == a[m])
              return m;
          else if (key < a[m])
               r = m - 1;
          else
              l = m + 1;
          }
          return -1;
     }
int main(int argc, char const* argv[]) {
    int n, key;
    std::cout << "Enter size of array: ";
    std::cin >> n;
    std::cout << "Enter array elements: ";
    int* a = new int[n];
//this loop use for store value in Array
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
        }
    std::cout << "Enter search key: ";
    std::cin >> key;
//this is use for find value in given array
    int res = binary_search(a, 0, n - 1, key);
    if (res != -1)
       std::cout << key << " found at index " << res << std::endl;
    else
       std::cout << key << " not found" << std::endl;
    return 0;
}