1247C - p-binary - CodeForces Solution

// Problem: C. p-binary
// Contest: Codeforces Round #596 (Div. 2, based on Technocup 2020 Elimination Round 2)
// URL: https://codeforces.com/contest/1247/problem/C
// Memory Limit: 512 MB
// Time Limit: 2000 ms
// Create Time : 2023-02-06 17:27:36
// 
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>
#define per(i, a, n) for (int i = n - 1;i >= a;i --)
#define rep(i, a, n) for (int i = a;i < n;i ++)
#define all(x) x.begin(), x.end()
#define SZ(x) ((int)(x).size())
#define PII pair<int, int>
#define int long long
#define PB push_back
#define se second 
#define endl "\n"
#define fi first 

using namespace std;
const int N = 5e5 + 50, mod = 1e9 + 7, INF = 1e18;
int t, n, m;

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    cin >> n >> m;
    int ok = -1;
    rep (i, 1, 32) {
    	int x = n - m * i, cnt = 0;
    	if (x < 0)  continue;
    	 rep (j, 0, 32) {
    	 	if (x >> j & 1) {
    	 		cnt ++;
    	 	}
    	 }
    	 // 少了并 多了没办法
    	 if (cnt <= i and x >= i) {
    	 	ok = i;
    	 	break;
    	 }
    }
    cout << ok << endl;

    return 0;
}