ExpressionEvaluator

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Stack;

public class ExpressionEvaluator {

    public static int evaluateExpression(String expression){

        Stack<Integer> sob = new Stack<Integer>();
        Stack<Integer> mnoz = new Stack<Integer>();
        boolean mnozi = false;
        int i, zbir = 0;
        char c;
        boolean in = false;
        int br = 0;
        int proiz;

        for (i=0; i<expression.length(); i++) {
            c = expression.charAt(i);

            if (Character.isDigit(c)) {

                if (!sob.isEmpty() && in) {
                    br = sob.pop();
                    br = br*10+Integer.parseInt(String.valueOf(c));
                    sob.push(br);
                } else {
                    sob.push(Integer.parseInt(String.valueOf(c)));
                    in = true;
                }
            }

            if (c == '*') {
                br = sob.pop();
                mnoz.push(br);
                in = false;
            }
            if (c == '+') {

                if (!mnoz.isEmpty()) {
                    proiz = 1;
                    while (!mnoz.isEmpty()) {
                        proiz = sob.pop() * mnoz.pop();
                        sob.push(proiz);
                    }
                }

                in = false;
            }
        }

        if (!mnoz.isEmpty()) {

            br = sob.pop();
            while (!mnoz.isEmpty()) {
                br *= mnoz.pop();
            }
            sob.push(br);
        }

        while (!sob.isEmpty()) {
            zbir += sob.pop();
        }

        return zbir;
    }

    public static void main(String[] args) throws IOException {
        BufferedReader input=new BufferedReader(new InputStreamReader(System.in));
        System.out.println(evaluateExpression(input.readLine()));
    }

}