from operator import itemgetter
from itertools import *
from bisect import *
from collections import *
from heapq import *
import sys

sys.setrecursionlimit(10 ** 6)

def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def SI(): return sys.stdin.readline()[:-1]
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
int1 = lambda x: int(x) - 1
def MI1(): return map(int1, sys.stdin.readline().split())
def LI1(): return list(map(int1, sys.stdin.readline().split()))
p2D = lambda x: print(*x, sep="\n")
dij = [(1, 0), (0, 1), (-1, 0), (0, -1)]

def main():
    inf=10**16
    n=II()
    c,v=MI()
    dp=[inf]*(n+1)
    dp[1]=0
    for i in range(1,n):
        pre=dp[i]
        if pre==inf:continue
        for j in range(1,n+1):
            ni=i+j*i
            if ni>n:ni=n
            val=pre+c+v*j
            dp[ni]=min(dp[ni],val)
            if i+i*j>n:break
    print(dp[n])

main()