#include <bits/stdc++.h>
int func(int a) { return (a + 1) * a / 2 * 5; }
int main() {
  int n, k, t, l, r, x, m;
  scanf("%d %d", &n, &k);
  t = 240 - k;
  l = 0;
  r = n;
  while ((r - l) > 1) {
    m = (r + l) / 2;
    x = func(m);
    if (x == t) {
      printf("%d", m);
      return 0;
    } else if (x > t) {
      r = m;
    } else if (x < t) {
      l = m;
    }
  }
  if (func(r) <= t)
    printf("%d", r);
  else
    printf("%d", l);
  return 0;
}
