#include <fstream>
using namespace std;
ifstream cin("jumatate1.in");
ofstream cout("jumatate1.out");
long long n,x,y,p,nr,i,r;
int main()
{cin>>n;
x=n;
while(x)
{
    nr++;
    x/=10;
}
y=0;p=1;
for(i=1;i<=(nr+1)/2;i++)
{
    y=y+(n%10)*p;
    p*=10;n/=10;
}
x=n;

while(y)
{
    r=x%y;
    x=y;
    y=r;
}
cout<<x;
}