money_change problem

#include<iostream>
#include<algorithm>
using namespace std;
bool compare(int a,int b)
{
	return a<=b;

}
int main()
{
	int coin[]={20,30,100,50};
	int n=sizeof(coin)/sizeof(int);
	int money;
	cout<<"enter the money ";
	cin>>money;
	while(money>0)
	{
	
	int index=lower_bound(coin,coin+n,money,compare)-coin-1;
	cout<<coin[index]<<endl;
	money=money-coin[index];
}
}