import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

from math import gcd

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

L = A*B//gcd(A,B)

T -= 1
answer = (T//A) + (T//B) - (T//L) + 1
print(answer)