Compilare: user.c:3: warning: return type of ‘main’ is not ‘int’ user.c: In function ‘main’: user.c:5: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:6: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result