#include <bits/stdc++.h>
using namespace std;
void swap(char* a, char* b) {
  char t = *a;
  *a = *b;
  *b = t;
}
void bubblesort(char array[], int n) {
  int i, j;
  bool swapped;
  for (i = 0; i < n - 1; i++) {
    swapped = false;
    for (j = 0; j < n - i - 1; j++) {
      if (array[j] > array[j + 1]) {
        swap(&array[j], &array[j + 1]);
        swapped = true;
      }
    }
    if (swapped == false) break;
  }
}
void swapit(int* a, int* b) {
  int t = *a;
  *a = *b;
  *b = t;
}
void bubble(int array[], int n) {
  int i, j;
  bool swapped;
  for (i = 0; i < n - 1; i++) {
    swapped = false;
    for (j = 0; j < n - i - 1; j++) {
      if (array[j] > array[j + 1]) {
        swapit(&array[j], &array[j + 1]);
        swapped = true;
      }
    }
    if (swapped == false) break;
  }
}
void lowercase(char array[], int n) {
  for (int i = 0; i < n; i++) {
    if (array[i] < 97) array[i] = array[i] + 32;
  }
}
bool isprime(int n) {
  int count = 0;
  int flag = 0;
  for (int i = n - 1; i > 1; i--) {
    if (n % i == 0) {
      flag++;
    }
  }
  if (flag > 0)
    return false;
  else
    return true;
}
int main() {
  int n, k;
  cin >> n >> k;
  int i = 1;
  int time = 0;
  while (i <= n) {
    time = time + (5 * i);
    if (time <= 240 - k)
      i++;
    else
      break;
  }
  cout << i - 1;
  return 0;
}
