#include <iostream>

int main() 
{
	float oceny[1020];
	
	for( int i = 0; i < 1020; i ++ )
	{
		float tmp;
		std::cin >> tmp;
		
		if( tmp == -1 ) break;
		else if( tmp == 0 ) 
		{
			for( int j = 0; j < i; j ++ )
			{
				std::cout << oceny[j];
			}
		}
		else if( tmp == 1 )
		{
			int sr = 0;
			for( int j = 0; j < i; j ++ ) sr += oceny[j];
			sr /= i;
			std::cout << sr;
		}
		else oceny[i] = tmp;
		
		std::cout << std::endl;
	}
	
	return 0;
}