One day, the professor called ABC three people and put three notes prepared in advance on their foreheads respectively. Then the professor said, "each of you has a note on your forehead, and each note has a positive integer written on it." You three can see the numbers on your heads except yourselves, but you are not allowed to peek at the numbers on your heads. In addition, I also tell you that one of these three numbers is the sum of the other two.

"If we now know that the number on A is 78, can you infer the numbers on B and C based on the above information?