import math

N, A, B = map(int, input().split())
lcm = A * B // math.gcd(A, B)
count_A = N // A + 1       
count_B = N // B + 1       
count_AB = N // lcm + 1    

bad = count_A + count_B - count_AB
answer = N + 1 - bad
print(answer)