import java.util.Scanner;

public class PostfixFilled {

    public static void main(String [] args) {

	Stack operands = new Stack();
	
	// We are restricted to single-digit inputs
	char[] expression = {'7','5','-','4','*','6','1','2','+','/','+'};

	for(int i = 0; i < expression.length; i++) {
	    
	    // Case 1: the next token is a number
	    if(Character.isDigit(expression[i])) {
		// Translate the next character into an int,
		// then push it onto the operands stack
		operands.push(Character.getNumericValue(expression[i]));
	    }

	    // Case 2: the next token is an operator
	    else {

		int b = operands.pop();
		int a = operands.pop();
		char op = expression[i];

		// Our next action depends on what operator we saw
		if(op == '+') operands.push(a + b);
		else if(op == '-') operands.push(a - b);
		else if(op == '*') operands.push(a * b);
		else operands.push(a / b);
	    }
	}

	// Print out the result of the computation
	System.out.println(operands.pop());


    }


}