Compilare: user.c: In function ‘main’: user.c:4: warning: unused variable ‘k’ 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:7: 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 user.c:4: warning: ‘pmax’ may be used uninitialized in this function