#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG_
#include <compe/debug.hpp>
#else
#define dump(...)
#endif

#define FastIO cin.tie(nullptr), ios_base::sync_with_stdio(false);
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define output(msg) cout << (msg) << '\n'
#define die(msg)         \
  do {                   \
    cout << msg << endl; \
    exit(0);             \
  } while (0)
#define all(k) k.begin(), k.end()
#define INFi 1 << 30
#define INFll 1LL << 60

template <typename T> bool chmax(T& a, const T& b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> bool chmin(T& a, const T& b) {
  return ((a > b) ? (a = b, true) : false);
}

using llint = long long int;

int main() {
  FastIO;
  int a, b, c, d, e;
  cin >> a >> b >> c >> d >> e;

  if (b <= c) die(0);
  b -= c;

  int sum{}, x = d;
  for (int i = 1; i <= b * a; ++i) {
    if (i == 1) {
      sum += x;
    } else {
      if (i % 10 != 0) {
        sum += x;
      } else if (i % 10 == 0 && e <= x) {
        x -= e;
        sum += x;
      } else {
        sum += x;
      }
    }
  }

  output(sum);
}