赛码网----股神

import java.util.Scanner;

public class Main {
    public static int solven(int n) {
        int addNum = 1, ans = 1, day = n - 1;
        while(day > addNum) {
            ans += addNum - 1;
            day -= ++addNum;
        }
        return ans + day;
    }
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        while(cin.hasNext()) {
            int n = cin.nextInt();
            System.out.println(solven(n));
        }
    }
}