n = int(input())
mi = 0
ma = n
while mi != ma:
    m = (mi + ma) // 2 + 1
    if m * m <= n:
        mi = m
    else:
        ma = m - 1
a = mi
if a * (a + 1) <= n:
    print(a + n // (a + 1))
else:
    print(a-1+n//a)