N,A,B = map(int, input().split())
if B>=2*A:
    print((N-1)*A-N*B)
elif A>B:
    if N%2==0:
        print(-(N-1)*A)
    else:
        print(-(N-1)*A-B)
else:
    if N%2==1:
        print(-(N-1)*A-B)
    else:
        if N==2:
            print(A-2*B)
        else:
            print(-(N-3)*A-2*B)