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#include <cstdio>
#include <vector>
using namespace std;

struct safety {
	int length;
	int unvaxxedEnds;
};

void main1() {
	int n;
	scanf("\n%d\n", &n);
	vector<safety> v;
	
	char c, cc = '1';
	for(int i=0; i<n; i++) {
		scanf("%c", &c);
		
		if(c == '0') {
		    if (cc == '0') {
    			v.back().length++;
		    } else {
			    v.push_back({ 1, 2 });
		    }
			if (i == 0) {
			    v.back().unvaxxedEnds--;
			}
			if (i + 1 == n) {
			    v.back().unvaxxedEnds--;
			}
		}
		cc = c;
	}
	
	bool hasSpread = !v.empty();
	while(hasSpread) {
	    hasSpread = false;
	    
	    int max = -1, maxIndex = -1;
	    for(int i=0; i<v.size(); i++) {
	        if ((max < v[i].length || (max == v[i].length && v[i].unvaxxedEnds < 2)) && v[i].unvaxxedEnds > 0) {
	            max = v[i].length;
	            maxIndex = i;
	        }
	    }
	    if (maxIndex >= 0) {
	        v[maxIndex].unvaxxedEnds--;
	        
    	    for(int i=0; i<v.size(); i++) {
    	        if (v[i].unvaxxedEnds > 0 && v[i].length > 0) {
    	            hasSpread = true;
        	        v[i].length -= v[i].unvaxxedEnds;
        	        if (v[i].length < 0) v[i].length = 0;
    	        }
    	    }
	    }
	}
	
    for(int i=0; i<v.size(); i++) {
        n -= v[i].length;
    }
    printf("%d\n", n);
}

int main() {
	int t;
	scanf("%d", &t);
	
	while(t--) main1();
	
	return 0;
}