#include <bits/stdc++.h>
using namespace std;
int main() {
  int problem, time;
  cin >> problem >> time;
  int sum = 240;
  int j = 0;
  for (int i = 1; i <= problem; ++i) {
    sum -= i * 5;
    if (sum < time) {
      break;
    }
    j++;
  }
  cout << j;
  return 0;
}
