simple infix2postfix conversion

Main.java

import java.io.*; 
import java.util.*; 


public class Main
{
    

static String infix2postfix(String input) 
{ 
    Stack<Character> temp_s = new Stack<>();  
    String result=""; 
    
    for(int i = 0; i < input.length(); ++i) 
    { 
        if(isOperand(input.charAt(i))) 
			result += input.charAt(i); 
        else if (input.charAt(i) == '(') 
			temp_s.push('('); 
        else if(input.charAt(i) == ')') 
        { 
            while(!temp_s.empty() && temp_s.peek() != '(') 
            { 
                result += temp_s.pop();
            } 
            if(temp_s.peek() == '(') 
            { 
                temp_s.pop(); 
            } 
        }  
        else { 
            while(!temp_s.empty() && priority(input.charAt(i)) <= priority(temp_s.peek())) 
            { 
                result += temp_s.pop();
            } 
            temp_s.push(input.charAt(i)); 
        } 
    } 
    while(!temp_s.empty()) 
    { 
        result += temp_s.pop();
    } 
    return result; 
} 

static int priority(char c) 
{ 
    if(c == '¬') return 5; 
    else if(c == '∧') return 4; 
    else if(c == '∨') return 3;
    else if(c == '→') return 2; 
    else if(c == '↔') return 1; 
    else return -1; 
} 

static boolean isOperand(char c){
	return ((c >= 'a' && c <= 'z')||(c >= 'A' && c <= 'Z'));
}
  
 
public static void main(String[] args) {
	System.out.println(infix2postfix("p∨q∧¬p∨r→q∨r"));   // out: pqp¬∧∨r∨qr∨→
	System.out.println(infix2postfix("((p∨q)∧(¬p∨r))→(q∨r)")); // out:pq∨p¬r∨∧qr∨→
}
}