/in/foo.c: In function 'main':
/in/foo.c:12:18: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long long int' [-Wformat=]
         printf("%d\n",2*a-1);
                  ^
/in/foo.c:6:18: warning: unused variable 'b' [-Wunused-variable]
     long long a, b;
                  ^