Infix and postfix are the notations to write the expressions. The infix notation put operators in between the operands. The postfix notation put operators after their operands. Write a program convert from infix notation to postfix notation.

Write a program to read the symbol string from the user. The program should validate the symbols using the stack. Stack uses push and pop operations for validating the symbol.

A stack is a basic data structure that insert and remove the items using last in first out (LIFO) strategy. The stack is a very powerful data structure. The stack can used when add or remove the element using last in first out order.

A linear data structure traverses the data items sequentially. The retrieval access only one data element at a time. The non linear data structure data elements are not organized in a sequential order. The data items are linked with other items and cannot be traversed in a single run.