static int evaluatePostfix(char [] izraz, int n)
    {
        ArrayStack<Character> e = new ArrayStack(n);
        char ch=0,res=0;
        int op1,op2,result=0;
        int z,i=0;
        while(i<n)
        {
             if(Character.isDigit(izraz[i]))
           {
             ch=izraz[i];
                 e.push(ch);

           }

            if(izraz[i]=='+' || izraz[i]=='-' || izraz[i]=='/' || izraz[i]=='*')
           {
               ch=izraz[i];

               op1 =e.pop()-'0';
                //System.out.print(e+op1+" ");

               op2 =e.pop()-'0';
                //System.out.print(op2+" ");

               if(ch=='+')
               {
               result=op1+op2;

               }
                if(ch=='-')
               {
                    if(op1>op2)
               result=op1-op2;
                    else
                        result=op2-op1;
               }
                if(ch=='/')
               {
                    if(op1==0 || op2==0)result=0;
                    else
               result=op1/op2;
               }
                if(ch=='*')
               {
               result=op1*op2;
               }
                 res=(char)(((int)'0')+result);
                 e.push((char)(((int)'0')+result));

           }
            i++;

           }


        return result;
}