import java.util.*; import java.io.*; public class Main { public static void main(String[] args) throws Exception { Scanner sc = new Scanner(); long n = sc.nextLong(); if (n % 2 == 0) { n /= 2; } long ans = 0; for (long i = 1; i <= Math.sqrt(n); i++) { if (n % i == 0) { ans += i; if (i * i < n) { ans += n / i; } } } System.out.println(ans); } } class Scanner { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(""); public Scanner() throws Exception { } public int nextInt() throws Exception { return Integer.parseInt(next()); } public long nextLong() throws Exception { return Long.parseLong(next()); } public double nextDouble() throws Exception { return Double.parseDouble(next()); } public String nextLine() throws Exception { return br.readLine(); } public String next() throws Exception { if (!st.hasMoreTokens()) { st = new StringTokenizer(br.readLine()); } return st.nextToken(); } }