Make it Anagram - using functional programming style - kind of new to Julia

MakeItAnagram4.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

class Solution {
    static void Main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution */
    
        var s1 = Console.ReadLine();
        var s2 = Console.ReadLine();
        
        var c1 = s1.GroupBy(c => c).ToDictionary(g => g.Key, g => g.Count());
        var c2 = s2.GroupBy(c => c).ToDictionary(g => g.Key, g => g.Count());
        
        int res = 0;
        
        foreach(var k in c1.Keys) {
            var diff = c1[k] - (c2.ContainsKey(k) ? c2[k] : 0);
            
            res += diff > 0 ? diff : 0;
        }
        
        foreach(var k in c2.Keys) {
            var diff = c2[k] - (c1.ContainsKey(k) ? c1[k] : 0);
            
            res += diff > 0 ? diff : 0;
        }
        
        Console.WriteLine(res);
    }
}