Compilare: user.c: In function ‘main’: user.c:95: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:96: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:98: warning: ignoring return value of ‘gets’, declared with attribute warn_unused_result user.c:120: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:123: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘factor’: user.c:88: warning: control reaches end of non-void function /tmp/ccr2f6EN.o: In function `main': user.c:(.text+0x1da): warning: the `gets' function is dangerous and should not be used.