$(document).ready(function(){
    $('#e1, #s').focus(function(){
        if (!this.has_changed) {
            this.initial_value = this.value;
            this.value='';
        }
    });

    $('#e1, #s').blur(function(){
        if (this.value == '') 
            this.value = this.initial_value;
        else
            this.has_changed = true;
    });
})