#include <iostream>
#include <sstream>

int main()
{
	int n;
	std::cin >> n;

	std::stringstream ans;

	int first = 0, last;
	for (int i = 0; i < n; ++i)
	{
		std::cin >> last;
		if ( last - first >= 2 )
			ans << first + 1 << '-' << last - 1 << '\n';
		first = last;
	}

	if ( last < 100 )
		ans << last + 1 << '-' << 100 << '\n';
	
	std::cout << ans.str();

	return 0;
}