foo.c: In function 'Mul':
foo.c:33:9: warning: 'return' with a value, in function returning void
  return 1;
         ^
foo.c:3:6: note: declared here
 void Mul(char number1[],char number2[])
      ^~~
foo.c: In function 'main':
foo.c:40:17: warning: implicit declaration of function 'iota' [-Wimplicit-function-declaration]
  char m1[10000]=iota(pow(x1,n1));
                 ^~~~
foo.c:40:22: warning: implicit declaration of function 'pow' [-Wimplicit-function-declaration]
  char m1[10000]=iota(pow(x1,n1));
                      ^~~
foo.c:40:22: warning: incompatible implicit declaration of built-in function 'pow'
foo.c:40:22: note: include '<math.h>' or provide a declaration of 'pow'
foo.c:40:17: error: invalid initializer
  char m1[10000]=iota(pow(x1,n1));
                 ^~~~
foo.c:41:17: error: invalid initializer
  char m2[10000]=iota(pow(x2,n2));
                 ^~~~
foo.c:42:6: warning: passing argument 1 of 'Mul' makes pointer from integer without a cast [-Wint-conversion]
  Mul(m1[10000],m2[10000]);
      ^~
foo.c:3:6: note: expected 'char *' but argument is of type 'char'
 void Mul(char number1[],char number2[])
      ^~~
foo.c:42:16: warning: passing argument 2 of 'Mul' makes pointer from integer without a cast [-Wint-conversion]
  Mul(m1[10000],m2[10000]);
                ^~
foo.c:3:6: note: expected 'char *' but argument is of type 'char'
 void Mul(char number1[],char number2[])
      ^~~
foo.c:39:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d",&x1,&n1,&x2,&n2);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务