/in/foo.c: In function 'main':
/in/foo.c:20:27: warning: passing argument 5 of 'step' from incompatible pointer type [-Wincompatible-pointer-types]
  printf("%c",step(p,q,m,n,a));
                           ^
/in/foo.c:3:5: note: expected 'int *' but argument is of type 'char (*)[100]'
 int step(int p, int q, int m, int n, int a[]);
     ^~~~
/in/foo.c: In function 'step':
/in/foo.c:30:19: error: subscripted value is neither array nor pointer nor vector
  if( q<m-1 && a[p][q+1]=='0' )
                   ^
/in/foo.c:35:21: error: subscripted value is neither array nor pointer nor vector
  if( p<n-1 && a[p+1][q]=='0' )
                     ^