Kamehameha

Read problems statements in Mandarin Chinese here City of Byteland can be described as a $2D$ grid of cells. Each cell may or may not contain a demon. You are given the list of cells that contain demons. In a single Kamehameha attack, Goku can kill all the demons standing in a row or in a column. But using Kamehameha drains Goku's power. You are to tell the minimum number of Kamehameha attacks t