N=int(input())
C,V=map(int,input().split())

DP=[1<<63]*(N+1)
DP[1]=0

for i in range(1,N):
    x=DP[i]

    now=x+C
    v=i

    while v<=N:
        v+=i
        now+=V
        DP[min(v,N)]=min(DP[min(v,N)],now)

print(DP[-1])