/in/foo.c: In function 'main':
/in/foo.c:8:26: error: expected ')' before 'b'
     printf("%ld%ld%ld",a b sum);
                          ^
/in/foo.c:8:18: warning: format '%ld' expects a matching 'long int' argument [-Wformat=]
     printf("%ld%ld%ld",a b sum);
                  ^
/in/foo.c:8:21: warning: format '%ld' expects a matching 'long int' argument [-Wformat=]
     printf("%ld%ld%ld",a b sum);
                     ^
/in/foo.c:5:15: warning: variable 'sum' set but not used [-Wunused-but-set-variable]
  long int a,b,sum;
               ^~~