For closed nmanifolds M and N with the form $M\simeq M^{n1}\cup _{f}e^n $,$N\simeq N^{n1}\cup _{d}e^n$
Why $M\sharp N \simeq (M^{n1}\vee N^{n1})\cup _{f+d}e^n$?
For closed nmanifolds M and N with the form $M\simeq M^{n1}\cup _{f}e^n $,$N\simeq N^{n1}\cup _{d}e^n$ Why $M\sharp N \simeq (M^{n1}\vee N^{n1})\cup _{f+d}e^n$? 

