#!/usr/bin/env python3
INF = 10 ** 16
def main():
    T = int(input())
    X, A = map(int, input().split())
    Y, B = map(int, input().split())
    if T > 0:
        p, q = divmod(T, A)
        path1 = p * X + q # A + walk
        if q == 0:
            print(path1)
            return
        back = A - q
        tt, ss = divmod(back, B)
        if ss == 0:
            path2 = (p + 1) * X + tt * Y
            print(min(path1, path2))
        else:
            backagain = B - ss
            path2 = (p + 1) * X + (tt + 1) * Y + backagain # A + B + walk
            print(min(path1, path2))
    else:
        p, q = divmod(-T, B)
        back = B - q
        if q == 0:
            print(p * Y)
        else:
            tt, ss = divmod(back, A)
            print((p + 1) * Y + tt * X + ss)
    return

if __name__ == '__main__':
    main()