#include <iostream>
using namespace std;
int LenString(char* str)
{
	int i = 0;
	while (str[i]) i++;
	return i - 1;
}
int main() {
	char a[80];
	gets_s(a);

	int count = 1;
	int sum = 0;
	for (int i = 0; i <= LenString(a); i++) {
		if (a[i] == '0'|| a[i] == '1' || a[i] == '2' || a[i] == '3' || a[i] == '4' || a[i] == '5' || a[i] == '6' || a[i] == '7' || a[i] == '8' || a[i] == '9') {
			++count;
			if (count % 2 == 0) {
				sum += (a[i]-48) ;
			}
			else sum -= (a[i]-48) ;
		}
	}

	cout<<"sum = " << sum;

	return 0;
}