def partial (R, s, partd):
m = 1000
E = m.powermod(s,R)
for k in range(1, s + 1):
Dk = math.floor((k * (R - 2 * isqrt(R) + 1) + 1) / s)
l=(partd).ndigits()
Dk=Dk-(Dk % 10^l)+partd
mm = E.powermod(Dk,R)
if m == mm:
return(Dk)
print("not enough digits to discover d")