#include <iostream>
#include <cmath>
using namespace std;

class EOF_Exception : public exception {};

// Input an integer in a loop until given a valid number
int inputInteger(const char* message){
	int n;

	while(1){
		cout << message;
		cin >> n;

		// Throw exception if end-of-file (EOF) is given on input
		if(cin.eof()) throw EOF_Exception();

		// Break this loop only the input is valid, otherwise print and error and redo.
		if(!cin.fail()) break;
		cout << "ERROR: Invalid integer input" << endl; 
	}

	return n;
}

// A struct to hold the bounds and length() for the number of ..numbers.. in the range.
typedef struct {
	int lower;
	int upper;

	int length(){ return upper - lower + 1; }
} Range;

// Inputs the bounds in a loop until valid bounds are given (lower <= upper)
Range inputRange(){
	Range range;

	while(1){
		range.lower = inputInteger("Enter lower limit: ");
		range.upper = inputInteger("Enter upper limit: ");

		// Break this loop only the range is valid, otherwise print and error and redo.
		if(range.lower <= range.upper) break;
		cout << "ERROR:" "lower bound (" << range.lower << ") is greater than " \
				 "upper bound (" << range.upper << ")" << endl;
	}

	return range;
}

// Iterates the given range and performs the summation + count of even numbers
// NOTE: Calculating the even/odd numbers can be done directly from the bounds without a loop
// which is probably better. I didn't bother, but you can lol =)
// NOTE: Printing is also done here for simplicity, but it is preferable to avoid mixing
// "user interface" operations (like printing to console) with "business logic" (our algorithm).
void iterate_range(Range range){
	int sum = 0, num_odds = 0;

	// NOTE: I thought of making a custom iterator to make this more elegant, but for
	// simplicity I've left it the way it is
	for(int n = range.lower; n <= range.upper; ++n){
		sum += n;
		if(sum % 2) ++num_odds;

		// Printing the sum, spaces are added only in between (it annoys me otherwise)
		if(n != range.lower) cout << " ";
		cout << sum;
	}
	// Print a new line character at the end of the lsit of sums printed in the loop.
	cout << endl;

	cout << "Even nubmers: "  << range.length() - num_odds << endl;
	cout << "Odd numbers: " << num_odds << endl;
}

// The entry point to the program.
int main(int argc, char **argv){
	try{
		Range range = inputRange();
		iterate_range(range);
	}
	catch(EOF_Exception& e){
		return 1;
	}

	return 0;
}