Compilare: user.cpp: In function ‘int main()’: user.cpp:31:24: warning: suggest parentheses around comparison in operand of ‘&’ [-Wparentheses] if(prime[i]&1==1) ^ user.cpp:8:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pairs.in","r",stdin); ^ user.cpp:9:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pairs.out","w",stdout); ^ user.cpp:12:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:14:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ user.cpp:26:21: warning: ‘j’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(!square[j]){ ^