#include<bits/stdc++.h>
using namespace std;
int main(){
	string s1,s2;
	cin>>s1>>s2;
	if(s2.size()>s1.size()){
		for(int i=0;i<s1.size();i++){
			if(s1[i]!=s2[i]) cout<<s1[i]-s2[i];
			return 0;
		}
	}
	else if(s1.size()>s2.size()){
		for(int i=0;i<s2.size();i++){
			if(s1[i]!=s2[i]) cout<<s1[i]-s2[i];
			return 0;
		}
	}else{
		cout<<0;
	}
	return 0;
}
/**************************************************************
	Problem: 1848
	User: zhangziang
	Language: C++
	Result: Wrong Answer
****************************************************************/