やるだけ

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

class  Rounder{
public:
	int round(int n, int b){
	
	int ans = 0;
	
	int flag = 0;
	int nau = 0;
	int sa = n;
	
	while(flag <= 2){
		nau += b;
		if(sa >= abs(n-nau)){
		sa = abs(n-nau);
		ans = nau;
		}
		if(nau > n) flag++;
	}
	
	return ans;	
	
}
};