#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); ++i)

int main() {
  int a, b;
  cin >> a >> b;
  constexpr double delta = 1e-7;
  double ans = 0;
  for (double l = a; l <= b; l += delta) {
    double y = (l - a) * (l - b);
    ans += delta * y;
  }
  cout << fixed << setprecision(15) << -ans << endl;
  return 0;
}