Compilare: user.cpp: In function ‘void main2()’: user.cpp:15:9: warning: unused variable ‘last’ [-Wunused-variable] int last=0; ^ user.cpp:11:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&v[1],&v[2],&v[3]); ^ user.cpp: In function ‘int main()’: user.cpp:97:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rgb.in","r",stdin); ^ user.cpp:98:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rgb.out","w",stdout); ^ user.cpp:101:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&t); ^