#include <bits/stdc++.h>
using namespace std;
int n, k, l, r, mid, a;
int main() {
  cin >> n >> k;
  a = 240 - k;
  l = 0;
  r = n + 1;
  while (r - l > 1) {
    mid = (r + l) / 2;
    if (5 * (mid * (mid + 1) / 2) > a) {
      r = mid;
    } else {
      l = mid;
    }
  }
  cout << l << endl;
  return 0;
}
