// Link ->
// Author -> Efat Sikder, IUBAT
#include "bits/stdc++.h"
using namespace std;
typedef long long int ll;
typedef unsigned long long l1;
typedef double db;
#define pi acos(-1)
#define prDouble(x, y) fixed << setprecision(y) << x
#define lcm(a, b) ((a * b) / __gcd(a, b))
#define fast_io \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL)
#define mm(x, v) memset((x), v, sizeof(x));
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define nl << "\n"
#define debug(x) cout << #x << " = " << x nl
#define casePrint(ans, cn) cout << "Case " << cn << ": " << ans nl
void solve(int caseNumber)
{
int n;
cin >> n;
string s;
cin >> s;
s += '1';
int ans = 0;
int zeroCnt = 0;
for (int i = 0; i <= n; i++)
{
if (s[i] == '0')
{
zeroCnt++;
}
else
{
ans = max(ans, zeroCnt);
zeroCnt = 0;
}
}
cout << ans nl;
}
void init_code()
{
fast_io;
}
signed main()
{
init_code();
int testcase = 1;
cin >> testcase;
for (int caseNumber = 1; caseNumber <= testcase; ++caseNumber)
{
solve(caseNumber);
}
return 0;
}