Compilare: main.cpp: In function 'int main()': main.cpp:23:13: warning: unused variable 'j' [-Wunused-variable] int k,i,j; ^ main.cpp:25:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("prim.in","r",stdin); ^ main.cpp:26:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&k); ^ main.cpp:29:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("prim.out","w",stdout); ^