#include <bits/stdc++.h>
using namespace std;
long long l, r, f, n, m, k, p, i, lm, rm;
int main() {
  cin >> n >> m >> k;
  l = k - 1;
  r = n - k;
  i = 1;
  m -= n;
  while (m > 0) {
    if ((i - 1) < r)
      rm = (i - 1);
    else
      rm = r;
    if ((i - 1) < l)
      lm = (i - 1);
    else
      lm = l;
    if (lm == l && rm == r) break;
    m = m - lm - rm;
    if (m > 0) {
      i++;
      m--;
    }
  }
  if (m > 0) i += m / n;
  cout << i << endl;
}
