@ after deleting C we can have 7 element
____ ____ ______ _______ _______ ________ __________
after 7 places A goes to any where so A have 7 possibility
reamining six places D every time come to first
and remaining five place G comes after E
and H comes after F so formula is 5!/2!*2!=30 devided by 2! two time becuase G comes after E
H comes after F
so 7*30=210
and same for node C 7*30=210
so overall =420