In every grid below, each row and column should contain 2 dots and 1 letter. The letter M indicates it is the Midpoint of the dots in its row and column. The letter N indicates it is between the dots but Not the midpoint. The letter O indicates it is Outside the dots. Fill in the missing symbols and dots. A sample puzzle is shown below. Each puzzle below has a unique solution. All puzzles copyright Erich Friedman, 2010.