Fill in some of the blank squares with the letters C or F. Each row and column should contain exactly 2 of each letter. Also, in each row and column, the distance between the C's is less than the distance between the F's. In other words, the C's are Closer and the F's are Farther. A sample puzzle is shown below. Each puzzle below has a unique solution. All puzzles copyright Erich Friedman, 2011.