#include <bits/stdc++.h>
using namespace std;
int maxProblemsToSolve(int n, int p) {
int sum = 0;
int count = 0;
int remainingTime = 240 - p;
for (int i = 1; i <= n; ++i) {
sum += 5 * i;
if (sum <= remainingTime) {
count++;
}
}
return count;
}
int main() {
int n, p;
cin >> n;
cin >> p;
cout<< maxProblemsToSolve(n, p);
}
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