Compilare: user.c: In function ‘comb’: user.c:6:5: warning: implicit declaration of function ‘sqrt’ [-Wimplicit-function-declaration] return (1+ sqrt(1+ 8 * p)) /2; ^ user.c:6:16: warning: incompatible implicit declaration of built-in function ‘sqrt’ [enabled by default] return (1+ sqrt(1+ 8 * p)) /2; ^ user.c: In function ‘main’: user.c:12:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sume.in","r",stdin); ^ user.c:13:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("sume.out","w",stdout); ^ user.c:14:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&nr); ^ user.c:18:15: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&v[i]); ^