#include <bits/stdc++.h>
using namespace std ;
int main() {
	char s[60];
	bool flag=false;
	while(cin>>s)
	{
		int n=0;
		for(int i=0;i<strlen(s); i++)
		{
			if(i%2) n-=s[i]-'0';
			else n+=s[i]-'0';
		}
		cout<<n<<endl;
		flag=true;
	}
	if(flag==false) cout<<"I finish the homework.\n";
}