when the condition is true not go stop the code PHP

How can i stop the code if $MinimumPay  >  $payment  is true then the code stop not go to another line



   if( $MinimumPay  >  $payment  )
      {  echo " you need to pay   $MinimumPay ";
      echo "<input name='Cancel' type='button' id='button2' value='cancel' onClick='history.go(-1)' /> " ;
      }
    if( $payment < 0  )
      {  echo "can not less than 0 ";
      echo "<input name='Cancel' type='button' id='button2' value='cancel' onClick='history.go(-1)' /> " ;
      }