#include <stdio.h>

int main()
{
	float money;
	while(scanf("%f",&money)!=EOF)
	{
		float change;
		float max=0;
		for(int i=0;i<12;i++)
		{
			scanf("%f",&change);
			if(max<change)
				max=change;
		}
		printf("%.2f\n",max*money);
	}
	return 0;
}
/**************************************************************
	Problem: 2031
	User: admin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:1144 kb
****************************************************************/