foo.c:9:13: error: unknown type name 'BigInt'
    9 | void Output(BigInt *p);
      |             ^~~~~~
foo.c:10:10: error: unknown type name 'BigInt'
   10 | void Pow(BigInt *p, int x);
      |          ^~~~~~
foo.c:11:10: error: unknown type name 'BigInt'
   11 | void Mul(BigInt *p1,BigInt *p2, BigInt *pAns);
      |          ^~~~~~
foo.c:11:21: error: unknown type name 'BigInt'
   11 | void Mul(BigInt *p1,BigInt *p2, BigInt *pAns);
      |                     ^~~~~~
foo.c:11:33: error: unknown type name 'BigInt'
   11 | void Mul(BigInt *p1,BigInt *p2, BigInt *pAns);
      |                                 ^~~~~~
foo.c: In function 'main':
foo.c:19:2: error: unknown type name 'BigInt'; use 'struct' keyword to refer to the type
   19 |  BigInt x1;
      |  ^~~~~~
      |  struct 
foo.c:20:4: error: request for member 'n' in something not a structure or union
   20 |  x1.n=1; x1.digit[1]=1;
      |    ^
foo.c:20:12: error: request for member 'digit' in something not a structure or union
   20 |  x1.n=1; x1.digit[1]=1;
      |            ^
foo.c:21:23: warning: implicit declaration of function 'Pow' [-Wimplicit-function-declaration]
   21 |  for(i=1; i<=n1; i++) Pow(&x1,a1);
      |                       ^~~
foo.c:23:2: error: unknown type name 'BigInt'; use 'struct' keyword to refer to the type
   23 |  BigInt x2;
      |  ^~~~~~
      |  struct 
foo.c:24:4: error: request for member 'n' in something not a structure or union
   24 |  x2.n=1; x2.digit[1]=1;
      |    ^
foo.c:24:12: error: request for member 'digit' in something not a structure or union
   24 |  x2.n=1; x2.digit[1]=1;
      |            ^
foo.c:27:2: error: unknown type name 'BigInt'; use 'struct' keyword to refer to the type
   27 |  BigInt x3;
      |  ^~~~~~
      |  struct 
foo.c:28:2: warning: implicit declaration of function 'Mul' [-Wimplicit-function-declaration]
   28 |  Mul(&x1, &x2, &x3);
      |  ^~~
foo.c:29:2: warning: implicit declaration of function 'Output' [-Wimplicit-function-declaration]
   29 |  Output(&x3);
      |  ^~~~~~
foo.c: At top level:
foo.c:32:10: error: unknown type name 'BigInt'
   32 | void Mul(BigInt *p1,BigInt *p2, BigInt *pAns)
      |          ^~~~~~
foo.c:32:21: error: unknown type name 'BigInt'
   32 | void Mul(BigInt *p1,BigInt *p2, BigInt *pAns)
      |                     ^~~~~~
foo.c:32:33: error: unknown type name 'BigInt'
   32 | void Mul(BigInt *p1,BigInt *p2, BigInt *pAns)
      |                                 ^~~~~~
foo.c:46:10: error: unknown type name 'BigInt'
   46 | void Pow(BigInt *p, int x)
      |          ^~~~~~
foo.c:63:13: error: unknown type name 'BigInt'
   63 | void Output(BigInt *p)
      |             ^~~~~~
foo.c: In function 'main':
foo.c:17:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   17 |  scanf("%d %d",&a1,&n1);
      |  ^~~~~~~~~~~~~~~~~~~~~~
foo.c:18:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   18 |  scanf("%d %d",&a2,&n2);
      |  ^~~~~~~~~~~~~~~~~~~~~~

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