Compilare: user.cpp: In function ‘void dfs2(int)’: user.cpp:57:23: warning: unused variable ‘mid’ [-Wunused-variable] int st,dr,mid,sol=q[0]; ^ user.cpp: In function ‘void bfs()’: user.cpp:113:23: warning: unused variable ‘mid’ [-Wunused-variable] int st,dr,mid,sol=q[0]; ^ user.cpp: In function ‘int main()’: user.cpp:147:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("harbingers.in","r",stdin); ^ user.cpp:148:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("harbingers.out","w",stdout); ^ user.cpp:150:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:154:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&u,&w,&d); ^ user.cpp:159:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld%lld",&prepare[i],&speed[i]); ^