// Including Libraries


# include < Wire.h >
# include < LiquidCrystal_I2C.h>
# include < math.h>

LiquidCrystal_I2C mydisplay(0x27,16,2);



// Define Input/Output Pins
# define solenoidpin 9
# define pot pin 1
#define ignitioninputpin 2
#define interruptnumber 0

// Defineing Variables
volatile int previousstate;
volatile byte buttonstate;
volatile int counter1;
volatile int start;
volatile int finish;
int elapsed;
int RPM;

// Main setup
void setup() {
  pinMode(solenoidpin, OUTPUT);
  pinMode(ignitioninputpin,INPUT);
  digitalWrite(ignitioninputpin,HIGH);
  attachInterrupt(1, isr_rpm, FALLING);
  counter1=1;

  mydisplay.init();
  mydisplay.backlight();
  mydisplay.setCursor(0,1);
  mydisplay.print(" Soleniod Motor ");

  previousstate=HIGH;
  Serial.begin(19200);
  buttonstate = digitalRead(ignitioninputpin);
}

// Main program loop
void loop() {

  buttonstate = digitalRead(ignitioninputpin);
  Serial.write("buttonstate");
  Serial.println(buttonstate);
  Serial.write("previousstate");
  Serial.println(previousstate);
  Serial.println(counter1);
  float elapsed=start=finish;
  float RPM= (6000/elapsed);

if  (buttonstate==LOW & previousstate==HIGH & (counter1%2)==0){
    digitalWrite(solenoidpin,HIGH);
  }

if  (buttonstate==HIGH & previousstate==LOW & (counter1%2)==0){
    digitalWrite(solenoidpin,HIGH);
  }

if  (buttonstate==LOW & previousstate==HIGH & (counter1%2)==0){
    digitalWrite(solenoidpin,LOW);
  }

if  ((counter1%2)==0){
    finish=start;
    start=millis();
  }

if  ((counter1%6)==0){
    mydisplay.setCursor(0,0);
    mydisplay.print(" RPM ");
    mydisplay.print(RPM);
    mydisplay.setCursor(0,1);
    mydisplay.print(" Solenoid Motor ");
  }
}
//Isr setup
void ISR() {
  buttonstate=LOW;
  counter1=counter1+1;
  previousstate=HIGH;
  }
}

Solenoid_motor:15: error: expected unqualified-id before string constant
Solenoid_motor:15: error: expected unqualified-id before 'void'
Solenoid_motor:15: error: expected `)' before 'void'
Solenoid_motor.ino: In function 'void setup()':
Solenoid_motor:34: error: 'isr_rpm' was not declared in this scope
Solenoid_motor.ino: At global scope:
Solenoid_motor:87: error: expected unqualified-id before string constant
Solenoid_motor:87: error: expected unqualified-id before 'void'
Solenoid_motor:87: error: expected `)' before 'void'
Solenoid_motor:92: error: expected declaration before '}' token