c++における一括読み出しとピクチャの格納

#include 
#include   
#include 
using namespace cv;
using namespace std;

int main()
{
	string fileName, grayFile;
	
	string str1, str2;
	Mat srcImage, grayImage;
	for (int i = 0; i <= 10; i++)
	{
		stringstream ss1, ss2;
		
    	ss1 << i;
		ss1 >> str1;
		//cout << str1 << endl;
		fileName = "" + str1 + ".jpg";
		srcImage = imread(fileName);

		grayFile = "out" + str1 + ".jpg";
		cvtColor(srcImage, grayImage, CV_BGR2GRAY);
		imwrite(grayFile, grayImage);
		
	}
	
	system("pause");
	return 0;
}