#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long t;
  t = 1;
  while (t--) {
    long long n, k;
    cin >> n >> k;
    vector<long long> v(n);
    for (long long i = 1; i <= n; i++) {
      v[i - 1] = 5 * i;
    }
    for (long long i = 1; i < n; i++) v[i] += v[i - 1];
    long long timeLeft = 240 - k;
    auto limit = lower_bound(v.begin(), v.end(), timeLeft);
    if (*limit > timeLeft) {
      limit--;
    }
    long long canSolve = limit - v.begin();
    if (canSolve != n) canSolve++;
    cout << canSolve << endl;
  }
  return 0;
}
