Compilare: user.c: In function ‘calc_sol’: user.c:18: warning: unused variable ‘last’ user.c:17: warning: unused variable ‘x’ user.c: In function ‘main’: user.c:44: warning: unused variable ‘j’ user.c:42: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:43: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:45: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:46: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result user.c:49: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result