Compilare: user.cpp: In function ‘void read()’: user.cpp:9:9: warning: unused variable ‘i’ [-Wunused-variable] int i,j,l,x; ^ user.cpp: In function ‘void write()’: user.cpp:51:19: warning: unused variable ‘j’ [-Wunused-variable] int sum=0,i=1,j,cost,l,c; ^ user.cpp: In function ‘void read()’: user.cpp:11:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("suma4.in","r",stdin); ^ user.cpp:12:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:19:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ user.cpp: In function ‘void write()’: user.cpp:48:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("suma4.out","w",stdout); ^