#include <bits/stdc++.h>
using namespace std;
#pragma comment(linker, "/STACK:1024000000,1024000000")
int _MAX(int a, int b) { return a > b ? a : b; }
int _MIN(int a, int b) { return a > b ? b : a; }
int Scan() {
  int res = 0, flag = 0;
  char ch;
  if ((ch = getchar()) == '-')
    flag = 1;
  else if (ch >= '0' && ch <= '9')
    res = ch - '0';
  while ((ch = getchar()) >= '0' && ch <= '9') res = res * 10 + (ch - '0');
  return flag ? -res : res;
}
void Out(int a) {
  if (a < 0) {
    putchar('-');
    a = -a;
  }
  if (a >= 10) Out(a / 10);
  putchar(a % 10 + '0');
}
int main() {
  int n, k;
  scanf("%d%d", &n, &k);
  int a = 240 - k, cnt = 0, mm = 5;
  while (mm <= a) {
    cnt++;
    a -= mm;
    mm += 5;
  }
  printf("%d\n", min(cnt, n));
  return 0;
}
