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