/in/foo.c: In function 'U':
/in/foo.c:5:12: warning: unused variable 'n' [-Wunused-variable]
  int i,j,m,n;
            ^
/in/foo.c: In function 'main':
/in/foo.c:24:2: error: expected declaration specifiers before 'scanf'
  scanf("%d%d",&n1,&n2);
  ^~~~~
/in/foo.c:25:2: error: expected declaration specifiers before 'for'
  for(j=0;j<n1;j++)
  ^~~
/in/foo.c:25:10: error: expected declaration specifiers before 'j'
  for(j=0;j<n1;j++)
          ^
/in/foo.c:25:15: error: expected declaration specifiers before 'j'
  for(j=0;j<n1;j++)
               ^
/in/foo.c:27:2: error: expected declaration specifiers before 'for'
  for(j=0;j<n2;j++)
  ^~~
/in/foo.c:27:10: error: expected declaration specifiers before 'j'
  for(j=0;j<n2;j++)
          ^
/in/foo.c:27:15: error: expected declaration specifiers before 'j'
  for(j=0;j<n2;j++)
               ^
/in/foo.c:29:2: error: expected declaration specifiers before 'U'
  U(b,n1);
  ^
/in/foo.c:30:2: error: expected declaration specifiers before 'printf'
  printf("\n");
  ^~~~~~
/in/foo.c:31:2: error: expected declaration specifiers before 'U'
  U(c,n2);
  ^
/in/foo.c:32:2: error: expected declaration specifiers before 'return'
  return 0;
  ^~~~~~
/in/foo.c:33:1: error: expected declaration specifiers before '}' token
 }
 ^
/in/foo.c:23:30: error: declaration for parameter 'j' but no such parameter
  int n1,n2,b[10000],c[10000],j;
                              ^
/in/foo.c:23:21: error: declaration for parameter 'c' but no such parameter
  int n1,n2,b[10000],c[10000],j;
                     ^
/in/foo.c:23:12: error: declaration for parameter 'b' but no such parameter
  int n1,n2,b[10000],c[10000],j;
            ^
/in/foo.c:23:9: error: declaration for parameter 'n2' but no such parameter
  int n1,n2,b[10000],c[10000],j;
         ^~
/in/foo.c:23:6: error: declaration for parameter 'n1' but no such parameter
  int n1,n2,b[10000],c[10000],j;
      ^~
/in/foo.c:33:1: error: expected '{' at end of input
 }
 ^