#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int main() {
	int N;
	scanf("%d", &N);
	char V[14];
	ll ans = (1ULL << 63) - 1;
	rep(ii, N) {
		scanf("%s", V);
		int len = strlen(V);
		rer(base, 2, 36) {
			ll x = 0;
			rep(i, len) {
				int d;
				if(V[i] <= '9')
					d = V[i] - '0';
				else
					d = V[i] - 'A' + 10;
				if(d >= base) { x = -1; break; }
//				cerr << i << ": " << x << ", " << x * base << ", " << d << ", " << x * base + d << endl;
				x = x * base + d;
			}
			if(x != -1)
				amin(ans, x);
		}
	}
	cout << ans << endl;
	return 0;
}