    program test02
     character*50 S
     character*3 ic
     integer N
     integer i, j
     integer :: countA=0
     
     read *,N
     read *,S
     
     do j=3,N
      i=j-2
      ic=S(i:j)
      if (ic=='ABC') then
       countA=countA+1
      end if
     end do
     
     print '(i0)', countA
 endprogram test02