Why do I get a "syntax error: unexpected token 'sampler2D'" or "redefinition of 'float4'".

Hello I get this error I don't know why, I followed a tutorial about dissolve effect because I am new on shaders, I did everything, but my shader doesn't works in my material and I think it's because of this error, when I change the order of sampler2D with float between the lines, the error changes too for a "redefinition of 'float4'.

Code (CSharp):

1. Shader "Unlit/Dissolve"
2. {
3.     Properties
4.     {
5.         _MainTex ("Texture", 2D) = "white" {}
6.         _DisolveTexture("Disolve Texture", 2D) = "white" {}
7.         _DisolveY("Current Y of the disolve effect", float) = 0
8.         _DisolveSize("Size of the effect", float) = 2
9.         _StartingY("Starting point of the effect", float) = -10
10.     }
11.     SubShader
12.     {
13.         Tags { "RenderType"="Opaque" }
14.         LOD 100
15.  
16.         Pass
17.         {
18.             CGPROGRAM
19.             #pragma vertex vert
20.             #pragma fragment frag
21.  
22.             #include "UnityCG.cginc"
23.  
24.             struct appdata
25.             {
26.                 float4 vertex : POSITION;
27.                 float2 uv : TEXCOORD0;
28.             };
29.  
30.             struct v2f
31.             {
32.                 float2 uv : TEXCOORD0;
33.                 float4 vertex : SV_POSITION;
34.                 float3 worldPos : TEXCOORD1;
35.             }
36.  
37.             sampler2D _MainTex;
38.             float4 _MainTex_ST;
39.             sampler2D _DisolveTexture;
40.             float _DisolveY;
41.             float _DisolveSize;
42.             float _StartingY;
43.            
44.  
45.             v2f vert (appdata v)
46.             {
47.                 v2f o;
48.                 o.vertex = UnityObjectToClipPos(v.vertex);
49.                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);
50.                 o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz
51.                 return o;
52.             }
53.  
54.             fixed4 frag (v2f i) : SV_Target
55.             {
56.                 float transition = _DisolveY - i.worldPos.y;
57.                 clip(_StartingY + (transition + (tex2D(_DisolveTexture,i.uv))* _DisolveSize))
58.                 // sample the texture
59.                 fixed4 col = tex2D(_MainTex, i.uv);
60.                
61.                 clip();
62.                 return col;
63.             }
64.             ENDCG
65.         }
66.     }
67. }
68.  

 

You're missing a semicolon at the closing brace of struct v2f