# Arup Guha
# 9/3/2020
# Voting Part B

# Get status of both candidates.
votesA = int(input("How many votes does candidate A have?\n"))
votesB = int(input("How many votes does candidate B have?\n"))

# We win by adding 1 to the difference.
print("Candidate A needs", (votesB-votesA+2)//2, "old voters of candidate B to switch their minds.")