1935

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) throws  IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		Stack<Double> stack = new Stack<>();
		int N = Integer.parseInt(br.readLine());
		String arr = br.readLine();
		Double[] data = new Double[N];
		
		for(int i=0;i<N;i++) {
			data[i] = Double.parseDouble(br.readLine());
		}
		
		for(int i=0;i<arr.length();i++) {
			if(arr.charAt(i)>='A'&&arr.charAt(i)<='Z') {
				stack.push(data[arr.charAt(i)-'A']);
			}
			else {	
				if(arr.charAt(i)=='*') {
					Double first = stack.pop();
					Double second = stack.pop();
					stack.push(second*first);
				}
				else if(arr.charAt(i)=='/') {
					Double first = stack.pop();
					Double second = stack.pop();
					stack.push(second/first);
				}
				else if(arr.charAt(i)=='+') {
					Double first = stack.pop();
					Double second = stack.pop();
					stack.push(second+first);
				}
				else {
					Double first = stack.pop();
					Double second = stack.pop();
					stack.push(second-first);
				}
			}
				
		}
		
		System.out.printf("%.2f", stack.peek());
		
	}
}