#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;
		for(int i=0;s.size()>i;i++)mx=max(mx,s[i]-(s[i]<='9'?47:54));
		for(int i=s.size();0<i;i--)z+=q*(s[s.size()-i]-(s[s.size()-i]<='9'?48:55)),q*=mx;
		if(ans==-1)ans=z;
		else ans=min(ans,z);
	}
	cout << ans << endl;
}