1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
#include <bits/stdc++.h>
using namespace std;
//{
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define VAR(v, i) __typeof(i) v=(i)
#define all(v) (v).begin(),(v).end()
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)


#define PII pair<int,int>
#define st first
#define nd second
#define pb push_back
#define lint long long int
#define VI vector<int>

#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
	*this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
};
//{
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

#define make( x) int (x); scanf("%d",&(x));
#define make2( x, y) int (x), (y); scanf("%d%d",&(x),&(y));
#define make3(x, y, z) int (x), (y), (z); scanf("%d%d%d",&(x),&(y),&(z));
#define make4(x, y, z, t) int (x), (y), (z), (t); scanf("%d%d%d%d",&(x),&(y),&(z),&(t));
#define makev(v,n) VI (v); FOR(i,0,(n)) { make(a); (v).pb(a);} 
#define IOS ios_base::sync_with_stdio(0)
#define HEAP priority_queue

#define read( x) scanf("%d",&(x));
#define read2( x, y) scanf("%d%d",&(x),&(y));
#define read3(x, y, z) scanf("%d%d%d",&(x),&(y),&(z));
#define read4(x, y, z, t) scanf("%d%d%d%d",&(x),&(y),&(z),&(t));
#define readv(v,n) FOR(i,0,(n)) { make(a); (v).pb(a);}
#define jeb() fflush(stdout);
//}

const int max_n = 1000005;

int n;
char s[max_n];

int bez_jedynek(VI& dwojki, int pocz_rnd) {
	int act = 0;
	int rnd = pocz_rnd;
	for (int i = dwojki.size() - 1; i >= 0; i--) {
		if (dwojki[i] <= 2*rnd) break;
		if (dwojki[i] <= 2*rnd + 2) {
			act++;
			rnd++;
		} else {
			act+=(dwojki[i] - 2*rnd - 1);
			rnd+=2;
		}
	}
	return act;
}

int main() {
	make(z); 
	while (z--) {
		read(n);
		scanf("%s", s);
		bool same = true;
		FOR(i,0,n) if (s[i] != s[0]) same = false;
		if (same) {
			if (s[0] == '0') printf("0\n");
			if (s[0] == '1') printf("%d\n", n);
			continue;
		}
		VI dwojki;
		VI jedynki;
		VI bloki;
		int cur = 0;
		FOR(i,0,n) {
			if (s[i] == '0') cur++;
			else {
				if (cur != 0) bloki.pb(cur);
				cur = 0;
			}
		}
		if (cur != 0) bloki.pb(cur);
		if (bloki.size() == 1) {
			if (s[0] == '0' || s[n-1] == '0') {
				printf("%d\n", n - bloki[0]);
				continue;
			} else {
				if (bloki[0] == 1) printf("%d\n", n - 1);
				else printf("%d\n", n - (bloki[0] - 1));
				continue;
			}
		}

		if (s[0] == '0') {
			jedynki.pb(bloki[0]);
		} else {
			dwojki.pb(bloki[0]);
		}
		if (s[n-1] == '0') {
			jedynki.pb(bloki.back());
		} else {
			dwojki.pb(bloki.back());
		}
		for (int j = 1; j < bloki.size() - 1; j++) {
			dwojki.pb(bloki[j]);
		}
		sort(all(dwojki));
		sort(all(jedynki));
		int best = 0;
		best = max(best, bez_jedynek(dwojki, 0));
		if (jedynki.size() > 0) {
			best = max(best, bez_jedynek(dwojki, 1) + jedynki.back());
		}
		if (jedynki.size() > 1) {
			best = max(best, bez_jedynek(dwojki, 2) + jedynki[0] + jedynki[1] - 1);
		}
		printf("%d\n", n-best);
	}
}