#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int f(char c) {
    if ('0' <= c && c <= '9') return c-'0';
    return c-'A'+10;
}

int main() {
    int n;cin>>n;
    ll ans = LLONG_MAX;
    for (int i=0;i<n;i++) {
        string s;
        cin>>s;
        int mx=0;
        for (char c:s) mx=max(mx,f(c)+1);
        ll d=0;
        for (char c:s) d=mx*d+f(c);
        ans=min(ans,d);
    }
    cout<<ans<<endl;
    return 0;
}