package assignment;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class main {
	public static void main(String args[]) throws FileNotFoundException {
		
		
		File f = new File("input.txt");
		
		Scanner scanner = new Scanner(f);
		int result = 0;
		result += scanner.nextInt();
		scanner.nextLine();
		int counter = 0;
	
		while(scanner.hasNextLine()) {
			String line = scanner.nextLine();
			String[] arr = line.split(" ");
		
			int max = 0;
		
			 int idx = counter;
				//	System.out.println(i);
				 int value1 = Integer.parseInt(arr[idx]);
				 int value2 =  Integer.parseInt(arr[idx+1]);
				 
				 
				 if(isPrime(value1)) {
					 max = value2;
					 counter = idx+1;
				 }
				 else if(isPrime(value2)) {
					 max = value1;
					 counter = idx;
				 }
				 else {
					 max = Math.max(value1, value2);
					 if(max==value1) {
						 counter = idx;
					 }
					 else {
						 counter = idx+1;
					 }
				 }
				
				 
			
			 result+=max;
			 
		}
		System.out.println("result: "+result);
		
	}
	static boolean isPrime(int val) {
		if(val<2) {
			return false;
		}
		for (int i = 2; i < val; i++) {
            if (val % i == 0) {
                return false;
                }
		}
        return true;
		
	}

}