package javacode;

import java.util.Scanner;

public class yukicoder2 {

	public static void main(String args[]){

		Scanner cin = new Scanner(System.in);

		int target = cin.nextInt();
		long tmp[] =new long[target];
		long result=0;

		for(int i=0;i<target;i++){
			tmp[i] = cin.nextLong();
		}
		for(int k=0;k<target;k++){
			if(k==0){
				result = tmp[0];
			}else if(tmp[k]==0L){

			}else{
				if(tmp[k]<1L){
					result += Math.abs(tmp[k]);
				}else{
					result *= tmp[k];
				}
			}
		}
		System.out.println(result);
	}
}