#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  m -= n;
  int esq = 0;
  int dre = 0;
  int res = 1;
  while (m > 0) {
    int pills = 1;
    pills += esq + dre;
    m -= pills;
    if (k - esq == 1 and k + dre == n) {
      ++res;
      res += m / pills;
      m = -1;
    }
    if (m >= 0) {
      ++res;
      if (k - esq > 1) ++esq;
      if (k + dre < n) ++dre;
    }
  }
  cout << res << endl;
}
