import java.util.Scanner;
import java.util.Stack;
import java.lang.*;
public class Infix {
public static double calculations(String here){
char[]chars = here.toCharArray();
MyStack<Character> operatorstack = new MyStack<Character>();
MyStack<Double> valuestack = new MyStack<Double>();
String operator;
char topOperator;
char nextCharacter;
double operandTwo;
double operandOne;
double result;
double next;
for(char c: chars)
{
//System.out.println("c is:" + c);
if(Character.isDigit(c)){
System.out.println("is a digit: " + c);
Double.parseDouble(Character.toString(c));
}
else {
operator = String.valueOf(c);
nextCharacter = c;
switch(nextCharacter) {

case '^':
operatorstack.push(nextCharacter);
break;


case '+':
case '-':
case '*':
case '/':

while(!operatorstack.isEmpty()&& getPriority(nextCharacter) <= getPriority(operatorstack.peek()))
{
// Calculate operator at the top of the stack.
topOperator = operatorstack.pop();
operandTwo = valuestack.pop();
operandOne = valuestack.pop();

if (topOperator == '*')
result = operandOne * operandTwo;
else if (topOperator == '/')
result = operandOne / operandTwo;
else if (topOperator == '+')
result = operandOne + operandTwo;
else if (topOperator == '-')
result = operandOne - operandTwo;
else
throw new RuntimeException("You can't do that, illegal operator: " + topOperator);

valuestack.push(result);
}
operatorstack.push(nextCharacter);
break;
default:
break;
}


}
while(!operatorstack.isEmpty()){
topOperator = operatorstack.pop();

operandTwo = valuestack.pop();

operandOne = valuestack.pop();


if (topOperator == '*')
result = operandOne * operandTwo;
else if (topOperator == '/')
result = operandOne / operandTwo;
else if (topOperator == '+')
result = operandOne + operandTwo;
else if (topOperator == '-')
result = operandOne - operandTwo;
else
throw new RuntimeException("You can't do that, illegal operator: " + topOperator);
valuestack.push(result);

}
}
double answer = valuestack.peek();
return answer;
}

public static int getPriority(char nextCharacter) {
if (nextCharacter == '*' || nextCharacter == '/')
return 1;
else if (nextCharacter == '+' || nextCharacter == '-')
return 2;
else if (nextCharacter == '=')
return 3;
else
return Integer.MIN_VALUE;

}
}