foo.c:7:1: error: unknown type name 'Bigint'; use 'struct' keyword to refer to the type
 Bigint d1, d2, ans;
 ^~~~~~
 struct 
foo.c:8:10: error: unknown type name 'Bigint'; did you mean 'int'?
 void Mul(Bigint* p, int x)
          ^~~~~~
          int
foo.c:23:11: error: unknown type name 'Bigint'; did you mean 'int'?
 void MULT(Bigint* p1, Bigint* p2, Bigint* pans)
           ^~~~~~
           int
foo.c:23:23: error: unknown type name 'Bigint'; did you mean 'int'?
 void MULT(Bigint* p1, Bigint* p2, Bigint* pans)
                       ^~~~~~
                       int
foo.c:23:35: error: unknown type name 'Bigint'; did you mean 'int'?
 void MULT(Bigint* p1, Bigint* p2, Bigint* pans)
                                   ^~~~~~
                                   int
foo.c: In function 'main':
foo.c:42:4: error: request for member 'n' in something not a structure or union
  d1.n = 1, d2.n = 1;
    ^
foo.c:42:14: error: request for member 'n' in something not a structure or union
  d1.n = 1, d2.n = 1;
              ^
foo.c:42:10: warning: left-hand operand of comma expression has no effect [-Wunused-value]
  d1.n = 1, d2.n = 1;
          ^
foo.c:43:4: error: request for member 'a' in something not a structure or union
  d1.a[0] = 1, d2.a[0] = 1; 
    ^
foo.c:43:17: error: request for member 'a' in something not a structure or union
  d1.a[0] = 1, d2.a[0] = 1; 
                 ^
foo.c:43:13: warning: left-hand operand of comma expression has no effect [-Wunused-value]
  d1.a[0] = 1, d2.a[0] = 1; 
             ^
foo.c:47:3: warning: implicit declaration of function 'Mul' [-Wimplicit-function-declaration]
   Mul(&d1, x1);
   ^~~
foo.c:50:2: warning: implicit declaration of function 'MULT'; did you mean 'NULL'? [-Wimplicit-function-declaration]
  MULT(&d1, &d2, &ans);
  ^~~~
  NULL
foo.c:51:14: error: request for member 'n' in something not a structure or union
  for (i = ans.n - 1; i >= 0; i--)
              ^
foo.c:52:19: error: request for member 'a' in something not a structure or union
   printf("%d", ans.a[i]);
                   ^
foo.c:45:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d", &x1, &n1, &x2, &n2);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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