/in/foo.c: In function 'main':
/in/foo.c:12:2: warning: implicit declaration of function 'system' [-Wimplicit-function-declaration]
  system("pause");
  ^~~~~~
/in/foo.c:4:21: warning: unused variable 'temp' [-Wunused-variable]
  int n, i, num = 0, temp;
                     ^~~~