If-else statement by user input in serial monitor

Hello everyone, i try to do if-else statement by using a user input in serial monitor. but everytime i enter a number on serial monitor, the print is not what i code. anyone please help, thank you

char value0;

void setup (){

Serial.begin(9600);
delay(200);

Serial.println("Enter Number: ");

}

void loop()
{
if( Serial.available())
{
value0 = Serial.read();

if((value0 > '39') && (value0 < '151'))
{
Serial.println("Play song 1");
}
else
{
Serial.println("Next song");
}

}
}