Arduino UNO, Program to follow light being developed, dont understand eroor mess

Hi everyone

I would kindly ask you for your help in identifying what this error message means, I am trying to develop a program which allows a shieldbot V1.2 robot to follow light, the program reads data from a0 and a1 each representing a sensor to left and right of the robot, then uses if statements to describe which sensor has higher more light reading, using the data it moves to the right or left direction. I have tried to compile this program below but comes up with an error message quote
‘sketch_apr06a.ino:41:1: error: stray ‘`’ in program’
can anyone please tell me what I am doing wrong?

#include <Shieldbot.h>
Shieldbot shieldbot = Shieldbot(); //decares a Shieldbot object

const int analogInPin0 = A0;
const int analogOutPin0 = 9;

const int analogInPin1 = A1;
const int analogOutPin1 = 9;

int sensorValue0 = 0;
int outputValue0 = 0;

int sensorValue1 = 0;
int outputValue1 = 0;

int Threshold = 100;
int Perc = 10;
int D = ((sensorValue1 - sensorValue0) / ((sensorValue1+ sensorValue0)/2)* 100);

void setup() {
//initialiase serial communications
Serial.begin(9600);
}

void loop() {
sensorValue0 = analogRead(analogInPin0);
outputValue0 = map(sensorValue0, 0, 1023, 0 , 255);
analogWrite(analogOutPin0, outputValue0);
sensorValue1 = analogRead(analogInPin1);
outputValue1 = map(sensorValue1, 0, 1023, 0, 255);
analogWrite(analogOutPin1, outputValue1);

delay(2);

if (outputValue1 && outputValue0 < Threshold) {
shieldbot.stop();
}
`
else if (outputValue1 < outputValue0 && D < Perc)
{
shieldbot.drive(0,200);
}

else if (outputValue0 < outputValue1 && D < Perc)
{
shieldbot.drive(200,0);
}

else if (D > Perc)
{
shieldbot.drive(200,200);
}

else if (D > Perc)
{
shieldbot.drive(200,200);
}

}

As the message says there is a stray apostrophe:

delay(2);

   if (outputValue1 && outputValue0 < Threshold) {
     shieldbot.stop();
   }
`  // what's this apostrophe for?

Seems pretty clear: The first character on line 41 is a "back-tick" - ` that does not belong there. Remove it.

Regards, Ray L.