A student needs to conduct a reaction that combines chemicals A and B to synthesize product AB. If we write this as a chemical equation it looks like: A+B→AB If this student combines 100 molecules of A and 100 molecules of B, the student obtains 100 molecules of AB. How many molecules of A would this student need to make 5000 molecules of AB? (Assume the student had enough of molecule B to make 5000 molecules of AB.) Express your answer as an integer.