import std.algorithm, std.array, std.container, std.range;
import std.numeric, std.math, std.bigint, std.bitmanip, std.random;
import std.string, std.conv, std.stdio, std.typecons;

void main()
{
  auto n = readln.chomp.to!int;
  auto vi = iota(n)
    .map!(_ => readln.chomp)
    .map!(s => s.map!(c => c >= '0' && c <= '9' ? c - '0' : c - 'A' + 10).map!(to!long).array);

  auto r = vi.map!(v => toLong(v, v.reduce!(max) + 1)).reduce!(min);

  writeln(r);
}

long toLong(long[] v, long radix)
{
  return iota(v.length).map!(i => v[i] * radix ^^ (v.length - i - 1)).sum;
}