N,A,B = map(int,input().split())
def gcd(a,b):
    if b==0:
        return a
    return gcd(b,a%b)
d = gcd(A,B)
C = A*B//d
na = N//A + 1
nb = N//B + 1
nc = N//C + 1
print(N+1-(na+nb-nc))