Compilare: user.c: In function ‘main’: user.c:17:1: warning: implicit declaration of function ‘sqrt’ [-Wimplicit-function-declaration] sqrtN = (int)sqrt((double)copyOfN); ^ user.c:17:14: warning: incompatible implicit declaration of built-in function ‘sqrt’ [enabled by default] sqrtN = (int)sqrt((double)copyOfN); ^ user.c:14:7: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(file1, "%d", &N); ^