#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, l = 0, s, t = 240;
  cin >> s >> k;
  t = t - k;
  int i = 1;
  while (t >= 0) {
    if (t - (i * 5) >= 0) {
      t = t - i * 5;
      l++;
      i++;
    } else
      break;
  }
  if (l >= s)
    cout << s;
  else
    cout << l;
  return 0;
}
