Compilare: user.cpp: In function ‘void solve()’: user.cpp:36:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0 ; i<v[x].size() ; i++) ^ user.cpp:31:11: warning: unused variable ‘i’ [-Wunused-variable] int x,i; ^ user.cpp: In function ‘void read()’: user.cpp:21:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n",&n,&m,&n1,&n2); ^ user.cpp:24:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&x,&y); ^ user.cpp: In function ‘int main()’: user.cpp:70:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.in","r",stdin); ^ user.cpp:71:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.out","w",stdout); ^