class StackObject {
    String str;
    int    loc;
    public StackObject(String s, int l) {
	str = s;
        loc = l;
    }
}

class MyStack<AnyType> {
    Object [] arr;
    int StackTop;
    public MyStack() {
	arr = new Object [20];
        StackTop = -1;
    }

    public void push (AnyType o) {
	StackTop++;
        arr[StackTop] = o;
    }
    public AnyType pop () {
	if (StackTop == -1) {return null;}
        else {
            StackTop--;
	    return (AnyType) (arr[StackTop + 1]);
	}
    }
}

class Auxiliaries {
    public static boolean matches(String a, String b) {
	boolean ans = false;
        if ((a == "(") && (b == ")")) ans = true;
        if ((a == "[") && (b == "]")) ans = true;
        return ans;
    }
}

public class ParanthGenerics {
    public static void main (String argv []) {
	String [] str = {"(", "[", "]", ")", "[", "]","("}; 
        //string to be processed
        StackObject ObjectOnTop;
        int i =  0; // to iterate through str
        boolean notDone = true;
        //variable to indicate mismatch in the middle of processing str
        MyStack<StackObject> sta = new MyStack<StackObject>();
        while( (i < str.length) && notDone) {

	    if ( (str[i] == "(") || (str[i] == "[")) {
		sta.push(new StackObject(str[i],i));
	    }
            // push onto stack for open paranths
            else if( (str[i] == ")") || (str[i] == "]") ) {
                ObjectOnTop =  sta.pop();
                // pop otherwise, and process as below
                if (ObjectOnTop == null) {
		    notDone = false;
                    System.out.println("The character " + str[i] + " at position" + i + "has no match");
		}
                else if (! Auxiliaries.matches(ObjectOnTop.str, str[i]) ) {
                    notDone = false;
		System.out.println("The " + str[i] + " at position " + i + " does not match the " + ObjectOnTop.str + " at position " + ObjectOnTop.loc);
		}
	    }
            else {System.out.println("invalid character at position" + i);}
            // Only used if str contains something other than paranths 

	
		i++;
	}

        if (sta.pop() != null) 
             System.out.println("Paranths need to be closed");
        
    }
}