foo.cc: In function ‘int main()’:
foo.cc:8:16: warning: zero-length gnu_printf format string [-Wformat-zero-length]
    8 |         printf("");
      |                ^~
foo.cc:6:13: warning: unused variable ‘max’ [-Wunused-variable]
    6 |         int max=0,a=0;
      |             ^~~
foo.cc:6:19: warning: unused variable ‘a’ [-Wunused-variable]
    6 |         int max=0,a=0;
      |                   ^