// Online C++ compiler to run C++ program online
#include <iostream>
using namespace std;

int binarySearch(int arr[], int size , int key) {
    int start = 0;
    int end = size-1;
    int mid = (start+end) / 2;
    
    while(start<=end){
        if(arr[mid] == key ){
            return mid ;
        }
        // go to right wala part 
        if(key > arr[mid]) {
            start = mid + 1;
            
        }
        else {
            end = mid -1 ;
        }
        mid =(start + end )/2;
        
    }
    return -1;
}

int main() {
    int even[6] ={2, 4, 8 , 10, 12 , 18};
    int odd[5] = { 3 , 5 , 7, 9, 11};
    
    
    int index = binarySearch(even , 6 ,10);
    cout << "index of 10 " << index << endl;
    
    int in = binarySearch(odd , 5 ,7);
    cout << "index of 7 " << in << endl;
    
    
    
    
    return 0;
}