#include <bits/stdc++.h>
using namespace std;
long n, m, k, c = 1, s = 1;
int main() {
  cin >> n >> m >> k;
  m -= n;
  while (m > 0) {
    if (k - c >= 1) s++;
    if (k + c <= n) s++;
    m -= s;
    c++;
  }
  cout << c;
  return 0;
}
