#include<iostream>
using namespace std;
int main(){int x,maxi,mini,c;cout<<"x=";cin>>x;maxi=x%10;mini=x%10;x/=10;while(x!=0){c=x%10;if (c!=0){if (c<mini) mini=c;if (c>maxi) maxi=c;}x/=10;}while(maxi!=mini)if (maxi>mini) maxi=maxi-mini; else mini=mini-maxi;cout<<maxi;}