#include <iostream>using namespace std;
int euclid (int a, int b) { int rest; while (b) { rest = a % b; a = b; b = rest; } return a;}
int main(){ int a,b,sumpar=0, sumimpar=0; cin>>b; if (b % 2 == 0 ) sumpar+=b; else sumimpar+=a; do { a=b; cin>>b; if (b % 2 == 0 ) sumpar+=b; else sumimpar+=b; } while (a!=b); if (sumimpar>0 && sumpar>0) if (sumpar<sumimpar) cout<<euclid(sumpar, sumimpar); else cout<<euclid(sumimpar, sumpar); return 0;}