Compilare: user.cpp: In function ‘bool cmpPoints(Point, Point)’: user.cpp:24:32: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] return a.x<b.x || a.x==b.x && a.y < b.y; ^ user.cpp: At global scope: user.cpp:35:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() { ^ user.cpp: In function ‘int main()’: user.cpp:52:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); i++) { ^ user.cpp:53:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i+1; j < a.size(); j++) { ^