Shader with texture with alpha and casting shadows

Hi.

I want a shader that renders a texture with alpha into something in which alpha is transparent and doesn't cast shadows and opaque part of the texture are indeed opaque and cast shadows. I managed to get this next shader but it seems that the whole texture is opaque to the engine.

 Shader "Custom/alphawithshadow"{
      Properties {
          _Color ("Main Color", Color) = (1,1,1,1)
          _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
      }
 
     SubShader {
         Tags {
             "Queue"="Transparent"
             "IgnoreProjector"="True"
             "RenderType"="Transparent"
             }
         LOD 200 Blend SrcAlpha OneMinusSrcAlpha
         CGPROGRAM #pragma surface surf Lambert addshadow
 
             sampler2D _MainTex;
             fixed4 _Color;
             struct Input {
                 float2 uv_MainTex;
             };
             
             void surf (Input IN, inout SurfaceOutput o) {
                 fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
                 o.Albedo = c.rgb;
                 o.Alpha = c.a;
             }
         ENDCG
 
     }
 
     Fallback "Transparent/VertexLit"
 }

The result is:

Though the texture is transparent on some part:

I am not good with shader coding. I just started learning it.