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