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- #include <iostream>
- #include <algorithm>
-
- using namespace std ;
-
- int main()
- {
- int n ;
- cin >> n ;
- int a[n] ;
- for(int i = 0 ; i < n ; ++i) cin >> a[i] ;
- sort(a,a+n) ;
- int x ;
- cin >> x ;
- int l = 0 , r = n ;
- while(r-l>1)
- {
- int mid = (r+l)/2 ;
- if(a[mid] <= x)
- l = mid ;
- else r = mid ;
- }
- if(a[l]==x)
- cout << l ;
- else
- cout << -1 ;
- }
-
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