#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: wangyichen2
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:1144 kb
****************************************************************/