Compilare: user.cpp: In function ‘int main()’: user.cpp:15:19: warning: unused variable ‘ans’ [-Wunused-variable] int i,j,S,N,F,ans; ^ user.cpp:12:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rec.in","r",stdin); ^ user.cpp:13:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rec.out","w",stdout); ^ user.cpp:17:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&S,&N,&F); ^