foo.cc: In function ‘int w(int, int, int)’:
foo.cc:9:37: warning: left operand of comma operator has no effect [-Wunused-value]
    9 |         else if(a<b and b<c)return (a,b,c-1)+w(a,b-1,c-1)-w(a,b-1,c-1);
      |                                     ^
foo.cc:9:43: warning: right operand of comma operator has no effect [-Wunused-value]
    9 |         else if(a<b and b<c)return (a,b,c-1)+w(a,b-1,c-1)-w(a,b-1,c-1);
      |                                           ^
foo.cc: In function ‘int main()’:
foo.cc:14:13: warning: unused variable ‘a’ [-Wunused-variable]
   14 |         int a,b,c;
      |             ^
foo.cc:14:15: warning: unused variable ‘b’ [-Wunused-variable]
   14 |         int a,b,c;
      |               ^
foo.cc:14:17: warning: unused variable ‘c’ [-Wunused-variable]
   14 |         int a,b,c;
      |                 ^