# import sys; input = sys.stdin.buffer.readline
# sys.setrecursionlimit(10**7)
from collections import defaultdict
# con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N = int(input())
	if N == 3:
		print(2)
		return

	n = int((N ** 0.5) // 1)
	if n ** 2 >= N:
		n -= 1
	# print(N ** 0.5, n)
	ans = int(N // (n + 1)) + n
	print(ans)
	

if __name__ == '__main__':
	main()