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

void mainSolve()
{
	int N;
	cin >> N;
	string str="";
	cin >> str;
	int c =0;
	for(int i=0;i<N;i++){
		if(str[i]=='1')
			c++;
	}
	for(int i=0;i<N-1;i++){
		if(str[i]==str[i+1] && str[i]=='1'){
			cout << 2 << endl;
			return;
		}
	}
	if(c==0)
		cout << 0 << endl;
	else 
		cout << 1 << endl;
}

int main()
{
  int t;
  cin >> t;
  while (t--)
  {
    mainSolve();
  }
  return 0;
}