Compilare: user.cpp: In function ‘int main()’: user.cpp:65:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<V.size();++j) ^ user.cpp:42:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sir4.in","r",stdin); ^ user.cpp:43:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sir4.out","w",stdout); ^ user.cpp:45:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d%d\n",&X,&A,&B,&M,&Q); ^ user.cpp:51:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S); ^ /tmp/ccFDkJeQ.o: In function `main': user.cpp:(.text.startup+0x14b): warning: the `gets' function is dangerous and should not be used.