from math import sqrt, floor


def main():
    N = int(input())
    n = floor(sqrt(N+1) - 1)

    if n * (n + 2) == N:
        print(n * 2)
        return

    if n*(n+2) + (n + 1) >= N:
        print(n*2 + 1)
        return
    if n*(n+2) + (n + 1) + (n+2) >= N:
        print(n*2+2)
        return

    if n*(n+2) + (n + 1) + 2*(n+2) >= N:
        print(n*2+3)
        return


if __name__ == "__main__":
    main()