import sys
sys.setrecursionlimit(10 ** 6)
INF = float('inf')
MOD = 10**9 + 7
def solve():
    def II(): return int(sys.stdin.readline())
    def LI(): return list(map(int, sys.stdin.readline().split()))
    def LC(): return list(input())
    def IC(): return [int(c) for c in input()]
    def MI(): return map(int, sys.stdin.readline().split())
    D = II()
    A,B = MI()
    Cost = INF
    for x in range(D+1):
        if(Cost>x*A+(D-x)*B):
            Cost = x*A+(D-x)*B
    print(Cost)
    return
solve()