#include <iostream>
using namespace std;
main(){
	int t;cin>>t;
	long long ans=-1;
	while(t--){
		string s;cin>>s;
		long long z=0,q=1;int mx=2,i=0;
		for(;s.size()>i;i++)mx=max(mx,s[i]-(s[i]<='9'?47:54));--i;
		for(;0<=i;i--)z+=q*(s[i]-(s[i]<='9'?48:55)),q*=mx;
		ans=min(z,(ans==-1?z:ans));
	}
	cout << ans << endl;
}