Compilare: main.cpp: In function 'void update(int, int, int, int, int)': main.cpp:83:14: warning: variable 'y1' set but not used [-Wunused-but-set-variable] int x1, x2, y1, y2; ^~ main.cpp:83:18: warning: variable 'y2' set but not used [-Wunused-but-set-variable] int x1, x2, y1, y2; ^~ main.cpp: At global scope: main.cpp:137:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] main() ^