/in/foo.c: In function 'main':
/in/foo.c:5:14: error: 'n' undeclared (first use in this function)
  scanf("%d",&n);
              ^
/in/foo.c:5:14: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:8:6: warning: implicit declaration of function 'su' [-Wimplicit-function-declaration]
   pu=su(b);
      ^~
/in/foo.c: In function 'su':
/in/foo.c:17:8: warning: unused variable 'ge' [-Wunused-variable]
  int i,ge,pan;
        ^~