I. I Like Short Statements

#include <bits/stdc++.h>
using namespace std;

using i64 = int64_t;
using i128 = __int128;

int main() {
    ios_base::sync_with_stdio(0), cin.tie(0);

    i64 N, M; cin >> N >> M;

    /// f(x) - f(x-1) = 2x-1 - sigma_1(x) ///

    auto f = [&](i128 x) -> i128 {
        /// find sum of (x mod i) = x - (x / i) * i ///

        i128 ans = x * x, i = 1;
        while (i <= x) {
            /// [x/j == x/i] --> [(x+1)/(x/i) < j <= x/(x/i)] ///
            i128 r = min(x / (x / i), x);
            ans -= (x / i) * (i + r) * (r - i + 1) / 2;
            i = r + 1;
        }
        return ans;
    };

    i64 lo = 0, hi = N, mi;
    while (lo < hi) {
        mi = (lo + hi + 1) >> 1;
        if (f(mi) <= M) lo = mi;
        else            hi = mi - 1;
    }

    i64 ans = lo;
    for (int d = 1; d <= 5; ++d) {
        if (lo + d <= N and f(lo+d) <= M) ++ans;
        if (lo - d >= 1 and f(lo-d) >  M) --ans;
    }
    cout << ans << "\n";

    return 0;
}