Compilare: user.cpp: In function ‘int main()’: user.cpp:25:9: warning: unused variable ‘i’ [-Wunused-variable] int i,j,K,p1,p2,O,V,ans; ^ user.cpp:25:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,K,p1,p2,O,V,ans; ^ user.cpp:22:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("drum3.in","r",stdin); ^ user.cpp:23:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("drum3.out","w",stdout); ^ user.cpp:27:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&N,&K); ^