# -*- coding: utf-8 -*-
import math
a, b, c = [int(i) for i in input().split()]
resultTime = min(b, c)
middleTime = 0
haveDone = 1
minNumber = resultTime
maxNumber = max(b, c)
while haveDone < a:
    middleTime += 1
    if middleTime % minNumber == 0 and middleTime == maxNumber:
        haveDone += 2
        resultTime += middleTime
        middleTime = 0
    elif middleTime == maxNumber:
        haveDone += 1
        resultTime += middleTime
        middleTime = 0
    elif middleTime % minNumber == 0:
        haveDone += 1
print(resultTime + middleTime)