from heapq import heappop, heappush
t = int(input())
x, a = map(int, input().split())
y, b = map(int, input().split())
dp = {0: 0}
hq = [(0, 0)]
while hq:
    _, p = heappop(hq)
    if p == t: break
    if p+1 not in dp or dp[p+1] > dp[p]+1:
        dp[p+1] = dp[p]+1
        heappush(hq, (dp[p+1], p+1))
    if p+a not in dp or dp[p+a] > dp[p]+x:
        dp[p+a] = dp[p]+x
        heappush(hq, (dp[p+a], p+a))
    if p-b not in dp or dp[p-b] > dp[p]+y:
        dp[p-b] = dp[p]+y
        heappush(hq, (dp[p-b], p-b))
print(dp[t])