#include <bits/stdc++.h>

using i32 = std::int32_t;
using u32 = std::uint32_t;
using i64 = std::int64_t;
using u64 = std::uint64_t;
using i128 = __int128_t;
using u128 = __uint128_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;

class rep {
    struct Iter {
        usize itr;
        constexpr Iter(const usize pos) noexcept: itr(pos) { }
        constexpr void operator ++ () noexcept { ++itr; }
        constexpr bool operator != (const Iter& other) const noexcept { return itr != other.itr; }
        constexpr usize operator * () const noexcept { return itr; }
    };
    const Iter first, last;
public:
    explicit constexpr rep(const usize first, const usize last) noexcept: first(first), last(std::max(first, last)) { }
    constexpr Iter begin() const noexcept { return first; }
    constexpr Iter end() const noexcept { return last; }
};

template <class T>
using Vec = std::vector<T>;

void A_main() {
    u32 A, B, C, D, E;
    std::cin >> A >> B >> C >> D >> E;
    u64 buy = A * (B - C);
    Vec<u64> X(buy + 1);
    X[1] = D;
    for (auto i: rep(2, buy + 1)) {
        if (i % 10 != 0) {
            X[i] = X[i - 1];
        }
        else {
            if (X[i - 1] >= E) {
                X[i] = X[i - 1] - E;
            }
            else {
                X[i] = X[i - 1];
            }
        }
    }
    std::cout << std::accumulate(X.begin(), X.end(), (u32) 0) << '\n';
    return;
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    A_main(); 
    return 0;
}