Compilare: user.cpp: In function ‘int main()’: user.cpp:32:9: warning: unused variable ‘a’ [-Wunused-variable] int a,b,c,d,ct=0; ^ user.cpp:32:13: warning: unused variable ‘c’ [-Wunused-variable] int a,b,c,d,ct=0; ^ user.cpp:32:15: warning: unused variable ‘d’ [-Wunused-variable] int a,b,c,d,ct=0; ^ user.cpp:30:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.in","r",stdin); ^ user.cpp:31:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.out","w",stdout); ^ user.cpp:34:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&b); ^