switch round(healt/25)
{  
case 0: draw_sprite(sprite0,0,x,y); break;  
case 1: draw_sprite(sprite1,0,x,y); break;  
case 2: draw_sprite(sprite2,0,x,y); break;  
case 3: draw_sprite(sprite3,0,x,y); break;  
case 4: draw_sprite(sprite4,0,x,y); break;  
}

switch healt
{
case 0: sprite_index=sprite1; break;
case 25: sprite_index=sprite2; break;
case 50: sprite_index=sprite3; break;
case 75: sprite_index=sprite4; break;
case 100: sprite_index=sprite5; break;
}

draw_sprite(sprite_index,0,x,y)