/in/foo.c: In function 'main':
/in/foo.c:37:13: warning: spurious trailing '%' in format [-Wformat=]
   printf("%%%",c,b,a);
             ^
/in/foo.c:37:10: warning: too many arguments for format [-Wformat-extra-args]
   printf("%%%",c,b,a);
          ^~~~~