//https://codeforces.com/problemset/problem/750/A

import java.util.*;
import java.io.*;

public class NewYearandHurry{
    public static void main(String[] arg) {
        Scanner scan = new Scanner(System.in);
        
        int n = scan.nextInt();
        int k = scan.nextInt();
        
        int solved = 0;
        int timeUsed = 0;
        
        for(int i=1; i<=n; i++) { // solving one question at a time
            if(timeUsed + k > 240){
                break;
            }
            timeUsed = timeUsed + i*5;
            solved++;
        }
        
        System.out.println(solved);
        
    }
}


// 5 10 15 
// total time to solve problems + time to travel to friend <= 240