T = int(input())
X,A = map(int,input().split())
Y,B = map(int,input().split())
ans = 10**20
low = max(0,(-T+B-1)//B)
for b in range(low,2*10**7+1):
    f = T+b*(B+Y)-(A-X)*((T+b*B)//A)
    ans = min(ans,f)
print(ans)