Compilare: user.cpp: In function ‘void preprocess()’: user.cpp:26:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<list[i].size();j++){ ^ user.cpp: In function ‘int main()’: user.cpp:41:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("amenzi.in","r",stdin); ^ user.cpp:42:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("amenzi.out","w",stdout); ^ user.cpp:44:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld %ld %ld",&n,&m,&k,&p); ^ user.cpp:47:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld %ld",&x,&y,&cost); ^ user.cpp:53:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld %ld",&x,&y,&cost); ^ user.cpp:60:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld",&x,&y); ^