Birthday Gift

Vamika is determined to present her mother Tupperware vessels. She offered $n$ vessels that might be both in blue shade or in pink shade. Her mother's preferred shade is pink, So she thought to present her most vessels in pink shade. She has confined paint to shade vessels. She was allowed to do precisely one move: she chooses indices $i$ and $j$ (1 ≤ i ≤ j ≤ n) and shaded all vessels for which th