/in/foo.c: In function 'main':
/in/foo.c:9:2: error: 'else' without a previous 'if'
  else if(n<2){
  ^~~~
/in/foo.c:25:15: warning: format '%ld' expects argument of type 'long int', but argument 2 has type 'long long int' [-Wformat=]
     printf("%ld",result);
               ^