#include <iostream>
#include <string>
#include <math.h>

int main()
{
	int result = 0;
	
	int count;
	std::cin >> count;
	
	std::string tiles;
	std::cin >> tiles;
	
	if(count < 9)
	{
		std::cout << 0 << std::endl;
		return 0;
	}
	
	int size = sqrt(count);
	int inner = pow(size - 2, 2);
	int outer = 4 * (size - 2) + 4;
	
	int sequenceSize = pow(size, 2);
	
	int color1 = 0;
	int color2 = 0;
	
	for(int i = 0; i < sequenceSize; i++)
	{
		if(tiles[i] == 'X') color1++;
		else color2++;
	}
	
	if((color1 == inner && color2 == outer) || (color1 == outer && color2 == inner)) result++;
	
	for(int i = 0; i < count - sequenceSize; i++)
	{
		if(tiles[i] == 'X') color1--;
		else color2--;
		
		if(tiles[i + sequenceSize] == 'X') color1++;
		else color2++;
		
		if((color1 == inner && color2 == outer) || (color1 == outer && color2 == inner)) result++;
	}
	
	std::cout << result << std::endl;
	
	return 0;
}