Compilare: user.cpp: In function ‘int main()’: user.cpp:9:9: warning: unused variable ‘a’ [-Wunused-variable] int n=0,a,b; ^ user.cpp:9:11: warning: unused variable ‘b’ [-Wunused-variable] int n=0,a,b; ^ user.cpp:7:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biti.in","r",stdin); ^ user.cpp:8:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biti.out","w",stdout); ^ user.cpp:10:21: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(si,nmax,stdin); ^