#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  scanf("%d %d %d", &n, &m, &k);
  int ans = 1;
  m -= n;
  int r = 0;
  int l = 0;
  while (m > 0) {
    ans++;
    m--;
    if (r < n - k) {
      r++;
      m -= r;
    } else
      m -= (n - k);
    if (l < k - 1) {
      l++;
      m -= l;
    } else
      m -= (k - 1);
  }
  printf("%d\n", ans);
  return 0;
}
