def floor(x,y):
    return x//y

def ceil(x,y):
    return (x+y-1)//y

def solve():
    T=int(input())
    X,A=map(int,input().split())
    Y,B=map(int,input().split())

    if T>0:
        K0=0
        K1=floor(T,Y)
    else:
        T_abs=abs(T)
        K0=ceil(T_abs,B)
        K1=floor(B,Y)+ceil(T_abs,B)

    Ans=float("inf")
    for r in range(K0,K1+1):
        q,p=divmod(T+r*B,A)
        Ans=min(Ans, p+q*X+r*Y)

    return Ans

print(solve())