Codeforces_750A

// Codeforces 750A

#include <iostream>

using namespace std;

int main()
{
    int all = 240, n, k, z = 1, rez = 0;
    cin >> n >> k;
    all -= k;
    while(all > 0)
    {
        if( all-(5*z) >= 0 )
        {
            all -= 5*z;
            rez++;
            z++;
        }
        if(rez == n){break;}
        else if(all-(5*z) < 0){break;}
    }
    cout << rez;
    return 0;
}