/in/ex4.c: In function 'main':
/in/ex4.c:62:5: error: implicit declaration of function 'atoi' [-Werror=implicit-function-declaration]
   n=atoi(*argv[i]);
     ^~~~
/in/ex4.c:58:12: error: unused variable 'flag' [-Werror=unused-variable]
  int n, i, flag=0;
            ^~~~
/in/ex4.c: In function 'compare':
/in/ex4.c:20:1: error: control reaches end of non-void function [-Werror=return-type]
 }
 ^
cc1: all warnings being treated as errors