def main():
    A, B, C, D, E = map(int, input().split())
    ans = 0
    P = [0] * 101010
    P[1] = D
    for i in range(2, 101010):
        X = P[i - 1]
        if i % 10 != 0:
            P[i] = X
        else:
            if E <= X:
                P[i] = X - E
            else:
                P[i] = X
    for i in range(B - C):
        for a in range(A):
            ans += P[i * A + a + 1]
    print(ans * A)


if __name__ == "__main__":
    main()