Note 3 - Securities - Available-for-sale Securities by Maturity (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
1-5 years, amortized cost	$ 434,711
1-5 years, fair value	434,909
6-10 years, amortized cost	10,751,633
6-10 years, fair value	10,600,771
After 10 years, amortized cost	25,585,848
After 10 years, fair value	24,990,481
Government sponsored mortgage-backed securities and SBA loan pools not due on a single maturity date, amortized cost	47,274,879
Government sponsored mortgage-backed securities and SBA loan pools not due on a single maturity date, fair value	45,917,263
Available-for-sale securities, amortized cost	84,047,071	$ 82,323,052
Available-for-sale securities	$ 81,943,424	$ 81,478,673

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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