int v0 = 0;
int v1 = 0;
int v2 = 0;
int v3 = 0;
int d0 = 0;
int d1 = 0;
int d2 = 0;
int d3 = 0;
const int indexPin = 26;
const int middlePin = 25;
const int ringPin = 12;
const int littlePin = 14;
const int chord[8][4] = {
  {100, 100, 41, 35}, // C
  {100, 100, 60, 8},  // Dm
  {100, 90, 65, 8},   // Em
  {100, 100, 60, 77}, // F
  {0, 75, 0, 100},    // G
  {100, 70, 87, 28},  // Am
  {100, 100, 52, 0},  // G7
  {0, 0, 0, 0}        // Muting
};
const String chord_name[8] = {
  "C", "Dm", "Em", "F", "G", "Am", "G7", "Muting"
};
void setup()
{
  pinMode(indexPin, INPUT);
  pinMode(middlePin, INPUT);
  pinMode(ringPin, INPUT);
  pinMode(littlePin, INPUT);
  Serial.begin(115200);
}

void loop()
{
  // read the sensor value:
  v0 = analogRead(indexPin);
  v1 = analogRead(middlePin);
  v2 = analogRead(ringPin);
  v3 = analogRead(littlePin);
  d0 = map(v0, 0, 4095, 0, 100);
  d1 = map(v1, 0, 4095, 0, 100);
  d2 = map(v2, 0, 4095, 0, 100);
  d3 = map(v3, 0, 4095, 0, 100);
  //print out the value you read:
  Serial.print("Index finger is  ");
  Serial.println(d0);
  Serial.print("Middle finger is ");
  Serial.println(d1);
  Serial.print("Ring finger is   ");
  Serial.println(d2);
  Serial.print("Little finger is ");
  Serial.println(d3);
  find_chord(d0, d1, d2, d3);
  delay(1000);
 }

void find_chord(int d0, int d1, int d2, int d3){
  int d[4] = {d0, d1, d2, d3};
  int mins = 401;
  int it = 0;
  for(int i=0; i<7; i++){
    if(d[0]+d[1]+d[2]+d[3] == 0){
      it = 7; break;
    }
    else if(d[0] + d[2] == 0){
      it = 4; break;
    }
    int s = 0;
    for(int j=0; j<4; j++){
      s += abs(d[j] - chord[i][j]);
    }
    if(mins > s){
      mins = s;
      it = i;
      Serial.print(chord_name[it]);
      Serial.print(" is more closer: ");
      Serial.println(s);
    }
  }
  Serial.print("Chord ");
  Serial.print(chord_name[it]);
  Serial.println(" is playing now.");
}