What a surprise, it does not compile

[matipacheco]

c--tic-tac-toe git:(master) g++ main.cpp -o main
main.cpp:40:22: error: a space is required between consecutive right angle
brackets (use '> >')
vector<vector<int>> lines{
^~
> >
main.cpp:40:30: error: expected ';' at end of declaration
vector<vector<int>> lines{
^
;
2 errors generated.

[Squirrels]

g++ assumes C++03 by default, and the syntax in this code uses C++11.

To compile it without this error, use
g++ -std=c++11 -o main main.cpp

Source: StackOverflow