Compilare: user.c: In function ‘heap_add’: user.c:31: warning: implicit declaration of function ‘upp’ user.c: In function ‘heap_del’: user.c:44: warning: implicit declaration of function ‘downn’ user.c: In function ‘main’: user.c:82: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:83: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:87: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:90: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:93: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:97: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘downn’: user.c:70: warning: control reaches end of non-void function user.c: In function ‘upp’: user.c:56: warning: control reaches end of non-void function