N = int(input())

import sys
s = set()
if N <= 100:
    for i in range(1,N + 5):
        s.add(N // i)
    print(len(s) - 1)
    exit()

start = 1
end = N
while end - start > 1:
    mid = end + start >> 1
    if mid * (mid + 1) <= N:
        start = mid
    else:
        end = mid
k = start
ans = k + N // (k + 1)
print(ans)