int mid = (n)/2;
        int temp = a[mid];
        a[mid] = a[n - 1];
        a[n - 1] = temp;
    
        int st = mid + 1;
        int ed = n - 2;
        while(st <= ed){
            temp = a[st];
            a[st] = a[ed];
            a[ed] = temp;
            st = st + 1;
            ed = ed - 1;
        }