#include <string>

#include "testlib.h"

int main() {
  registerValidation();

  const int N = inf.readInt(1, 2000);
  inf.readChar('\n');
  for (int i = 1; i < N; i++) {
    inf.readInt(2, 2000);
    inf.readChar(" \n"[i + 1 == N]);
  }
  const std::string M = inf.readString();
  inf.readEof();

  ensure(1 <= M.size() && M.size() <= 7000);
  for (const char d : M)
    ensure('0' <= d && d <= '9');
  ensure(M[0] != '0');
}