n, m, k = map(int, input().split()) ans = [-1] * n used = 0 for i in range(n): if k == 0: break if k >= n - 1 - i: ans[n - 1 - i] = i k -= n - 1 - i else: ans[k] = i k = 0 used += 1 for i in range(n): if ans[i] == -1: ans[i] = used used += 1 if used == n: ans[i] = m - (n - 1) * (n - 2) // 2 print(ans[i])