#include <iostream>

using namespace std;
int getLength(char array[100])
{
    int j = 0;
    for (int i = 0; array[i] != '\0'; i++)
    {
        j++;
    }
    return j;
}

int toNumber(char a){
    switch(a){
        case '0': return 0;
        case '1': return 1;
        case '2': return 2;
        case '3': return 3;
        case '4': return 4;
        case '5': return 5;
        case '6': return 6;
        case '7': return 7;
        case '8': return 8;
        case '9': return 9;
        default: return -1;
    }
}

void printArray(char array[100])
{
    int length = getLength(array);
    for (int i = 0; i < length; i++)
    {
        cout << array[i];
    }
}

bool isNumber(char a)
{
    return (a >= '0' && a <= '9');
}

bool isSymbol(char a)
{
    switch (a)
    {
    case '+': return true;
    case '-': return true;
    case '/': return true;
    case '*': return true;
    case '=': return true;
    default: return false;
    }

}

bool valid(char array[100], char newArray[100], int &j)
{
    bool number = false, symbol = false, equation = false;
    j = 0;
    int length = getLength(array);
    for (int i = 0; i < length; i++)
    {
        if (isNumber(array[i]) || isSymbol(array[i]))
        {
            newArray[j] = array[i];
            j++;
        }
    }

    if (isSymbol(newArray[0]))
    {
        return false;
    }

    for (int i = 0; i < j; i++)
    {
        if (isSymbol(newArray[i]) && symbol)
        {
            return false;
        }
        if (isSymbol(newArray[i]))
        {
            if (equation && newArray[i] == '=')
            {
                return false;
            }

            symbol = true;
            number = false;

            if (newArray[i] == '=')
            {
                equation = true;
            }

            continue;
        }
        if (isNumber(newArray[i]))
        {
            symbol = false;
            number = true;
        }

    }
    if (equation)
    {
        return false;

    }
    else
    {
        return true;
    }

}

int recursion(char array[100], int length, int position, int finalNumber = 0)
{

    if (length-1 == position)
    {
        return finalNumber;
    }

    if (position == 0)
    {
        finalNumber = toNumber(array[position]);
        position++;
    }

  //  cout << "Position: " << position << endl;
    //cout << "Array[i]: " << array[position] << endl;
   // cout << "finalNumber: " << finalNumber << endl;

    if (array[position] == '+')
    {
        finalNumber = finalNumber +  toNumber(array[position+1]);
        //cout << "Numbre+ : " << finalNumber << endl;
        return (recursion(array, length, position + 1, finalNumber));
    }

    if (array[position] == '-')
    {
        finalNumber = finalNumber -  toNumber(array[position+1]);
       // cout << "Numbre- : " << finalNumber << endl;
        return (recursion(array, length, position + 1, finalNumber));
    }

    if (array[position] == '*')
    {

        finalNumber = finalNumber *  toNumber(array[position+1]);
        //cout << "Numbre* : " << finalNumber << endl;
        return (recursion(array, length, position + 1, finalNumber));
    }

    if (array[position] == '/')
    {

        finalNumber = finalNumber / toNumber(array[position+1]);
       // cout << "Numbre/ : " << finalNumber << endl;
        return (recursion(array, length, position + 1, finalNumber));
    }

    return recursion(array, length, position+1, finalNumber);

}

//3-5+2*2 = 0
//4+5-6*6+3 = 21
int main()
{
    int length = 0;
    char array[100];
    char newArray[100];
    cin.getline(array, 100);
    int number = 0;

    if (valid(array, newArray,length))
    {

        number = recursion(newArray, length, 0);
        cout << number;
    }
}