#include <string.h>
#include <fstream.h>
#include <math.h>
#include <stdlib.h>

const int MAX_LENGTH = 35;
typedef char string[MAX_LENGTH];

string stack;
string postfix;
string input;
int index = 0;
int top = -1;

void push(char c) {
	if ( top < 35 )
		stack[++top] = c;
}

char pop() {
	if ( top > -1 )
		return stack[top--];
	return '~';
}

char peek() {
	if ( top > -1 )
		return stack[top];
	return '~';
}

void gotOperand(char ch, int prec1) {
	while ( top > -1 ) {
		char opTop = pop();
		if ( opTop == '(' ) {
			push(opTop);
			break;
		}
		else {
			int prec2;
			if ( opTop=='+' || opTop=='-' )
				prec2 = 1;
			else
				prec2 = 2;
			if ( prec2 < prec1) {
				push(opTop);
				break;
			}
			else
				postfix[index++] = opTop;
		}
	}
	push(ch);
}

void gotParen(char ch) {
	while ( top > -1 ) {
		char chx = pop();
		if ( chx == '(' )
			break;
		else
			postfix[index++] = chx;
	}
}

double evaluate() {
	int intRetVal[MAX_LENGTH];
	int dIndex = -1;
	for ( int i=0; i<=index; i++ ) {
		if ( postfix[i] >= '0' && postfix[i] <= '9' ) {
			intRetVal[++dIndex] = postfix[i] - 48;
		}
		else {
			int dTwo = intRetVal[dIndex--];
			int dOne = intRetVal[dIndex--];
			switch (postfix[i]) {
				case '+':
					intRetVal[++dIndex] = dOne + dTwo;
					break;
				case '-':
					intRetVal[++dIndex] = dOne - dTwo;
					break;
				case '*':
					intRetVal[++dIndex] = dOne * dTwo;
					break;
				case '/':
					intRetVal[++dIndex] = dOne / dTwo;
					break;
				default:
					intRetVal[++dIndex] = 0;
			}
		}
	}
	return intRetVal[0];
}

void main() {
	double dOutput = 0;

	ifstream InFile("algebra.txt");
	ofstream OutFile("postfix.txt");
	while ( InFile.peek() != EOF ) {
		InFile.getline(input, MAX_LENGTH);
		int l = strlen(input);
		for (int i=0; i<l; i++ ) {
			switch (input[i]) {
				case '+':
				case '-':
					gotOperand(input[i], 1);
					break;
				case '*':
				case '/':
					gotOperand(input[i], 2);
					break;
				case '(':
					push(input[i]);
					break;
				case ')':
					gotParen(input[i]);
					break;
				default:
					postfix[index++] = input[i];
					break;
			}
		}
		while ( top > -1 ) {
			postfix[index++] = pop();
		}
		dOutput = evaluate();
		OutFile << postfix << " = " << dOutput << "\n";
		index = 0;

	}
	InFile.close();
}