T, A, B = gets.split(" ").map{|s| s.to_i}

def gcd(a, b)
	return a if b == 0
	return gcd(b, a % b)
end

def lcm(a, b)
	return a * b / gcd(a, b)
end
	
C = lcm(A, B)

cnt = ((T-1) / A) + ((T-1) / B) - ((T-1) / C) + 1

puts cnt