diff --git a/lib/buildTonalnost/buildTonalnost.test.ts b/lib/buildTonalnost/buildTonalnost.test.ts
new file mode 100644
index 0000000..8d49a64
--- /dev/null
+++ b/lib/buildTonalnost/buildTonalnost.test.ts
@@ -0,0 +1,14 @@
+import { describe, it, expect } from "vitest";
+import { buildTonalnost } from "./buildTonalnost.ts";
+
+describe("buildTonalnost", () => {
+  let sortedArray = [-12, 1, 4, 6, 22];
+
+  it("buildTonalnost", () => {
+    expect(buildTonalnost(sortedArray, 4)).toBe(2);
+  });
+
+  it("buildTonalnost", () => {
+    expect(buildTonalnost(sortedArray, 3)).toBe(-1);
+  });
+});
diff --git a/lib/buildTonalnost/buildTonalnost.ts b/lib/buildTonalnost/buildTonalnost.ts
new file mode 100644
index 0000000..5e573ea
--- /dev/null
+++ b/lib/buildTonalnost/buildTonalnost.ts
@@ -0,0 +1,71 @@
+type Gamma = "A" | "B" | "C" | "D" | "E" | 'F' | "G";
+
+type BaseNote =
+  "A" | "B" | "C" | "D" | "E" | 'F' | "G" |
+  "Ab" | "Bb" | "Cb" | "Db" | "Eb" | "Fb" | "Gb" |
+  "Am" | "Bm" | "Cm" | "Dm" | "Em" | "Fm" | "Gm" |
+  "Abm" | "Bbm" | "Cbm" | "Dbm" | "Ebm" | "Fbm" | "Gbm";
+
+function buildGamma(baseNote: Gamma, poluton: string[], isBemol: boolean = false) {
+  const gamma = ['C', 'D', 'E', 'F', 'G', 'A', 'B'];
+  const gammaIndexNote = gamma.findIndex((n) => n === baseNote);
+  const gammaBaseNote = gammaIndexNote !== 0 ? [...gamma.slice(gammaIndexNote), ...gamma.slice(0, gammaIndexNote)] : gamma.slice(gammaIndexNote);
+
+  const resultGamma = gammaBaseNote.map(n => {
+    if (poluton.includes(n)) {
+      return isBemol ? n + "b" : n + "#";
+    }
+    return n;
+  })
+
+  return resultGamma;
+}
+
+
+export function buildTonalnost(baseNote: BaseNote) {
+  let res: string[] = [];
+  const searchSeaquencies = ['F', 'C', 'G', 'D', 'A', 'E', 'B'];
+  const gamma = ['C', 'D', 'E', 'F', 'G', 'A', 'B'];
+  const isMinor = baseNote.slice(-1) === 'm'
+  const isBemol = /b/.test(baseNote);
+  const isDies = !isBemol;
+  const note = baseNote.slice(0, 1);
+
+  if (isDies) {
+    const gammaIndexNote = gamma.findIndex((n) => n === note);
+    const prevNoteGammIndex = gammaIndexNote === 0 ? 6 : gammaIndexNote - 1;
+    const noteSearchSeq = gamma[prevNoteGammIndex];
+    const searchSeaquenciesIndex = searchSeaquencies.findIndex(n => n === noteSearchSeq);
+    const diesSlice = searchSeaquencies.slice(0, searchSeaquenciesIndex + 1)
+    res = buildGamma(note as Gamma, diesSlice)
+  }
+
+  if (isBemol) {
+    const searchSeaquenciesIndex = searchSeaquencies.findIndex(n => n === note);
+    const prevNoteSearchSeqIndex = searchSeaquenciesIndex === 0 ? 6 : searchSeaquenciesIndex - 1;
+    const bemoleSlice = searchSeaquencies.slice(prevNoteSearchSeqIndex);
+    res = buildGamma(note as Gamma, bemoleSlice, true)
+  }
+
+  if (isMinor) {
+    console.log({ isMinor })
+  }
+
+  return `note: ${baseNote}, gamma: ${res.join(' | ')}`;
+};
+
+
+console.log(buildTonalnost('A'))
+console.log(buildTonalnost('Ab'))
+console.log(buildTonalnost('B'))
+console.log(buildTonalnost('Bb'))
+console.log(buildTonalnost('C'))
+console.log(buildTonalnost('Cb'))
+console.log(buildTonalnost('D'))
+console.log(buildTonalnost('Db'))
+console.log(buildTonalnost('E'))
+console.log(buildTonalnost('Eb'))
+console.log(buildTonalnost('F'))
+console.log(buildTonalnost('Fb'))
+console.log(buildTonalnost('G'))
+console.log(buildTonalnost('Gb'))
diff --git a/lib/buildTonalnost/index.ts b/lib/buildTonalnost/index.ts
new file mode 100644
index 0000000..a197ded
--- /dev/null
+++ b/lib/buildTonalnost/index.ts
@@ -0,0 +1,3 @@
+import { buildTonalnost } from "./buildTonalnost";
+
+export default buildTonalnost;