Compilare: user.cpp: In function ‘int main()’: user.cpp:36:85: warning: suggest parentheses around ‘-’ in operand of ‘&’ [-Wparentheses] if(a[1].x*a[i].y+a[i].x*a[j].y+a[1].y*a[j].x-a[j].x*a[i].y-a[j].y*a[1].x-a[1].y&a[i].x==0&&j!=i) ^