#include <bits/stdc++.h>
//#define int long long
using namespace std;
int n, T, a[1000010];
int read()
{
	int x = 0, f = 1;
	char c = getchar();
	while(c != EOF and !isdigit(c))
	{
		if(c == '-')f = -1;
		c = getchar();
	}
	while(isdigit(c))
	{
		x = x * 10 + c - '0';
		c = getchar();
	}
	return x * f;
}
int lowbit(int x){
	return x & (-x);
}
string s;
signed main()
{
	T = read();
	while(T --)
	{
		n = read();
		int cnt = 0;
		cin>>s;
		for(int i = 1;i <= n;i ++)
		{
			a[i] = s[i - 1] - '0';
		}
		for(int i = 1;i <= n;i ++)
		{
			if(a[i] == 1)
			{
				int x = i;
				while(a[x] != 0)
				{
					a[x] = 2;
					x += lowbit(x);
				}
				if(x > n)cnt ++;
				else cnt += 2;
			}
		}
		cout<<cnt<<endl;
		for(int i = 0;i <= n;i ++)a[i] = 0;
	}
	return 0;
}