#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a, b, c, x = 0;
  cin >> a >> b >> c;
  b -= a;
  while (b >= 0) {
    if (min(x, c) == c && min(x - 1, a - c) == a - c) {
      x += (b / a) + 1;
      break;
    } else {
      x++;
      b -= min(x, c);
      b -= min(x - 1, a - c);
    }
  }
  cout << x;
}
