new to c++, getting error

[msae]

Hello, here is my simple program which I am trying to compile and run.

# include <iostream>

int main() 
{
	cout << "Hello World" << end1;
	int sum = 0;
	
	for(int index = 0; index <= 10; index++)
	{
		sum += index;
	}
	
	cout << "The sum is: " << sum << end1;
	
	return 0;
}

the name of file is firstCPlusPlus.cpp

When I enter 'g++ firstCPlusPlus.cpp into terminal window, get this error:

Undefined symbols:
"_main", referenced from:
start in crt1.10.6.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

Any help would be great. Thinking my code is alright but my compiler side of things is messed. New to the game of c++ and frustrated with this error

Thanks to all for any advice!