diff --git a/JinHaLim/Easy/solution_1791.js b/JinHaLim/Easy/solution_1791.js
new file mode 100644
index 0000000..ed288c9
--- /dev/null
+++ b/JinHaLim/Easy/solution_1791.js
@@ -0,0 +1,20 @@
+/**
+ * @param {number[][]} edges
+ * @return {number}
+ */
+var findCenter = function(edges) {
+    for (let i = 0; i < 2; i++) {
+        for (let j = 1; j < edges.length; j++) {
+            if (edges[j].includes(edges[0][i])) {
+                return edges[0][i];
+            }
+            else{
+                break;
+            }
+            
+        }
+        
+    }
+};
+console.log(findCenter([[1,2],[2,3],[4,2]]))
+console.log(findCenter([[1,2],[5,1],[1,3],[1,4]]))
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diff --git a/JinHaLim/Easy/solution_1913.js b/JinHaLim/Easy/solution_1913.js
new file mode 100644
index 0000000..6b59908
--- /dev/null
+++ b/JinHaLim/Easy/solution_1913.js
@@ -0,0 +1,9 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxProductDifference = function(nums) {
+    nums.sort((a,b) => b-a);
+    return (nums[0] * nums[1]) - (nums[nums.length-1] * nums[nums.length-2]);
+};
+console.log(maxProductDifference([5,6,2,7,4]))
\ No newline at end of file
diff --git a/JinHaLim/Easy/solution_1920.js b/JinHaLim/Easy/solution_1920.js
new file mode 100644
index 0000000..49b80c6
--- /dev/null
+++ b/JinHaLim/Easy/solution_1920.js
@@ -0,0 +1,13 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var buildArray = function(nums) {
+    let arr = nums.slice(0);
+    for (let i = 0; i < arr.length; i++) {
+        arr[i] = nums[nums[i]]
+        
+    }
+    return arr;
+};
+console.log((buildArray([0,2,1,5,3,4])))
\ No newline at end of file