参考程序：

#include<bits/stdc++.h>
using namespace std;
#define ll long long
int n, m;
int cnt[1010];
vector<int> cs[1010];
ll calc(int aim) 
{
	int cur_cnt = cnt[1];
	ll res = 0;
	vector<int> tmp;
	for (int i = 2; i<=n; i++)
	{
		int buy = max((int)cs[i].size() - aim + 1, 0);
		for (int j = 0; j < buy; ++j) 
		{
			res += (ll)cs[i][j];
		}
		cur_cnt += buy;
		for (int j = buy; j < cs[i].size(); ++j) 
		{
			tmp.push_back(cs[i][j]);
		}
	}
	sort(tmp.begin(), tmp.end());
	for (int i = 0; i < aim - cur_cnt; i++) 
	{
		res += (ll)tmp[i];
	}
	return res;
}
int main() 
{
	cin >> n >> m;
	for (int i = 1; i <=m; i++) 
	{
		int p, c;
		cin >> p >> c;
		cnt[p]++;
		cs[p].push_back(c);
	}
	for (int i = 1; i <=n; i++) 
	{
		sort(cs[i].begin(), cs[i].end());
	}
	ll ans = 1e18;

	for (int i = max(cnt[1], 1); i <= m; ++i) 
	{
		ans = min(ans, calc(i));
	}
	cout << ans << "\n";
}