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


if __name__ == '__main__':
    main()