N, A, B= map(int, input().split())
L = list(range(0, N + 1))
LA1 = []
LB2 = []
X1 = 1
if X1 * A <= N:
    X1 = X1 + 1 
    LA1.append(X1 * A)

X2 = 1
if X2 * B <= N:
    X2 = X2 + 1 
    LB2.append(X2 * B)      

L = set(LA1) | set(LB2)
print(N + 1 - len(L))