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