import static java.lang.System.out;
import java.util.Scanner;

public class No445{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		String sA=sc.next();
		String sB=sc.next();
		int n=toI(sA,6);
		int k=toI(sB,1000);
		int f=calc(n,k);
		if(f==0){out.println("error");}
		else{out.println(f);}
		sc.close();
	}
	
	private static int toI(String a,int max){
		try{
			int i=Integer.parseInt(a);
			if(i<=max){return i;}else{return 0;}
		}catch(NumberFormatException e){return 0;}
	}
	
	private static int calc(int n,int k){
		int f=50*n+(int)Math.floor(500*n/(8+2*k));
		return f;
	}
}