count fibonacci numbers as number of string over alphabet

class Fibonacci

{

static void Main(string[] args)

{

Dictionary obj = new Dictionary();

int n = 26, f = 1, k = -1, s = 0;

for (int i = 0; i < n; i++)

{

s = k + f;

k = f;

f = s;

int num = 65 + i;

char c = (char)num; //Convert ASCII value into char

int a = char.ToUpper('b');// convert char into ASCII value

//Add values in to the dictionary

obj.Add(c, s);

//Console.WriteLine(s);

}

string str;

str = Console.ReadLine().ToUpper();

int sum = 0;

for (int j = 0; j < str.Length; j++)

{

sum = sum + obj[str[j]];

}

Console.WriteLine(sum);

Console.ReadLine();

}