n=int(input())
tmp=0
for i in range(max(1, int(n**0.5)-2),max(1, int(n**0.5)+3)):
    if n/i-n/(i+1)<1:
        tmp=i
        break
if tmp!=0:
    print((tmp-1)+n//tmp)
else:
    s=set([])
    for i in range(1, n+1):
        s.add(n//i)
    print(len(set))