Compilare: main.cpp: In function 'double area(const std::vector<point>&)': main.cpp:23:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < pol.size()-1; i++) ~~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:54:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < polygon.size(); i++) ~~^~~~~~~~~~~~~~~~ main.cpp:57:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = i + 1; j < polygon.size(); j++) ~~^~~~~~~~~~~~~~~~ main.cpp:60:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = j + 1; k < polygon.size(); k++) ~~^~~~~~~~~~~~~~~~ main.cpp:63:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int l = k + 1; l < polygon.size(); l++) ~~^~~~~~~~~~~~~~~~