Compilare: user.cpp: In function ‘int main()’: user.cpp:9:7: warning: unused variable ‘j’ [-Wunused-variable] int i,j,k=0,n; ^ user.cpp:7:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] {freopen("euler.in","r",stdin); ^ user.cpp:8:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("euler.out","w",stdout); ^