////Given
E=4*10**3*1.6*10**-19
m0=9.1*10**-31
b=6.4*10**-16
d=102.39*10**-16
h=6.3*10**-34
c=3*10**8

//Calculation
//
p=sqrt(2*m0*E)
d=b+d
lembda=(2*h*c)/d

//Result
printf("\n Wavelength of incident photon is  %0.2f A",lembda*10**10)