import math

T, A, B = map(int, input().split())

count_A = (T - 1) // A + 1
count_B = (T - 1) // B + 1

gcd_ab = math.gcd(A, B)
lcm_ab = A * B // gcd_ab

count_lcm = (T - 1) // lcm_ab + 1

result = count_A + count_B - count_lcm
print(result)