int diff;
nMotorEncoder[leftMotor] = 0;
nMotorEncoder[rightmotor] = 0;
while (true)
{
    diff = (nMotorEncoder[rightMotor] - nMotorEncoder[leftMotor])/scaleFactor;
    motor[leftMotor] = 50 + diff;
    motor[rightMotor] = 50 - diff;
    wait1Msec(10);
}