import std.conv;
import std.stdio;
import std.range;
import std.array;
import std.algorithm;

void main() {
	
	auto vars = readln.split.map!(to!int).array;
	auto idxTask = iota(1, vars[0] + 1).map!(a => a * 5).array;

	auto sumFoldTask = cumulativeFold!((a, b) => a + b)(idxTask).array;

	int count;
	foreach (idx, el; sumFoldTask) {
		if (240 - el < vars[1]) {
			break;
		}
		++count;
	}

	writeln(count);
}