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

a=(T-1)//A+1
b=(T-1)//B+1

def gcd(A,B):
    if B>A:
        A,B=B,A
    while A%B!=0:
        A,B=B,A%B
    return B
c=(T-1)//(A*B//gcd(A,B))+1
print(a+b-c)