#include <bits/stdc++.h>
const int MAXN = 100 + 5;
int one, zero;
char str[MAXN];
int main(int argc, char *argv[]) {
  scanf("%*d%s", str);
  for (int i = 0; str[i]; i++)
    if (str[i] == '1')
      one++;
    else
      zero++;
  if (one)
    putchar('1');
  else
    putchar('0');
  if (one)
    for (int i = 0; i < zero; i++) putchar('0');
  return 0;
}
