A grid is divided into rectangular and square regions. Some cells contain numbers. Fill in some cells with black according to these rules:
Numbered cells remain white.
A number indicates the number of black cells around it, but one number per region is wrong.
Black cells cannot touch horizontally or vertically.
All white cells must be connected.
Usowan (one liar) is a logic puzzle where you blacken cells based on given numbers, but one number in each region is wrong. Black cells cannot touch and all white cells must be connected.