/in/foo.c: In function 'main':
/in/foo.c:74:19: warning: array subscript has type 'char' [-Wchar-subscripts]
          a[k-1][1][b[k-1][1]++]=j-1;
                   ^
/in/foo.c:75:19: warning: array subscript has type 'char' [-Wchar-subscripts]
          a[j-1][0][b[j-1][0]++]=k-1;
                   ^