#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;
typedef long long ll;

ll n, s, m, l, r;

int main()
{
    scanf("%I64d%I64d", &n, &s);
    ll tmp = (n * (n + (ll)1)) / (ll)2;
    if (tmp <= s)
    {
        if (tmp == s)
            printf("0\n");
        else
            printf("1\n");
        return 0;
    }
    s -= n;
    l = (ll)0;
    r = n - (ll)2;
    while (l < r)
    {
        m = (l + r + (ll)1) / (ll)2;
        tmp = (m * (m + (ll)1)) / (ll)2;
        if (tmp <= s)
            l = m;
        else
            r = m - (ll)1;
    }
    printf("%d\n", n - l - (ll)1);
    return 0;
}