#include <bits/stdc++.h>
using namespace std;
const int N = 1e3 + 10, M = 1e5;
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
vector<int> divisors(int n) {
  vector<int> ret;
  for (int i = 1; i <= n / i; ++i) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i != n / i) ret.push_back(n / i);
    }
  }
  return ret;
}
bool isPrime(int v) {
  if (v <= 1) return 0;
  for (int i = 2; i <= v / i; i += 1 + (i & 1)) {
    if (v % i == 0) return 0;
  }
  return 1;
}
int lcm(int x, int y) { return x * y / gcd(x, y); }
int k, l, m, n, d;
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  cin >> n >> k;
  int sum = 0;
  bool canMakeit = true;
  int i;
  for (i = 1; i <= n; ++i) {
    if ((sum + i * 5 + k) <= 240)
      sum += i * 5;
    else {
      canMakeit = false;
      break;
    }
  }
  cout << (i - 1) << '\n';
  return 0;
}
