#include<stdio.h>
int main()
{
	float a,b,c;
	scanf("%f%f%f",&a,&b,&c);
	printf("%.1f",a*8.5+b*5.6+c*6.2);
	return 0;
}
/**************************************************************
	Problem: 1610
	User: admin
	Language: C
	Result: Accepted
	Time:12 ms
	Memory:1144 kb
****************************************************************/