diff --git "a/\354\213\240\355\230\234\354\233\220/week5/backjoon_1026.js" "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1026.js"
new file mode 100644
index 0000000..3cae13b
--- /dev/null
+++ "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1026.js"
@@ -0,0 +1,13 @@
+const fs = require("fs");
+const input = fs.readFileSync(0, "utf8").trim().split("\n");
+
+let a = input[1].split(" ").map(Number);
+let b = input[2].split(" ").map(Number);
+
+a.sort((x,y)=> x-y);
+b.sort((x,y)=> y-x);
+let sum = 0;
+for(let i = 0; i < a.length; i++){
+    sum += a[i] * b[i];
+} 
+console.log(sum);
\ No newline at end of file
diff --git "a/\354\213\240\355\230\234\354\233\220/week5/backjoon_1057.js" "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1057.js"
new file mode 100644
index 0000000..17d9f0b
--- /dev/null
+++ "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1057.js"
@@ -0,0 +1,13 @@
+const fs = require("fs");
+const input = fs.readFileSync(0, "utf8").trim().split(" ").map(Number);
+
+let [N, a, b] = input;
+let count = 0;
+
+while (a !== b) {
+  a = Math.ceil(a / 2);
+  b = Math.ceil(b / 2);
+  count++;
+}
+
+console.log(count);
\ No newline at end of file
diff --git "a/\354\213\240\355\230\234\354\233\220/week5/backjoon_1091.js" "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1091.js"
new file mode 100644
index 0000000..3a9a1c1
--- /dev/null
+++ "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1091.js"
@@ -0,0 +1,49 @@
+const fs = require("fs");
+const input = fs.readFileSync(0, "utf8").trim().split("\n");
+
+const N = Number(input[0]);
+const P = input[1].split(" ").map(Number);
+const S = input[2].split(" ").map(Number);
+
+let cards = Array.from({ length: N }, (_, i) => i);
+const start = cards.slice();
+
+function check() {
+  for (let i = 0; i < N; i++) {
+    if (P[cards[i]] !== i % 3) return false;
+  }
+  return true;
+}
+
+function shuffle() {
+  const next = new Array(N);
+  for (let i = 0; i < N; i++) {
+    next[S[i]] = cards[i];
+  }
+  cards = next;
+}
+
+let answer = 0;
+
+while (true) {
+  if (check()) {
+    console.log(answer);
+    break;
+  }
+
+  shuffle();
+  answer++;
+
+  let same = true;
+  for (let i = 0; i < N; i++) {
+    if (cards[i] !== start[i]) {
+      same = false;
+      break;
+    }
+  }
+
+  if (same) {
+    console.log(-1);
+    break;
+  }
+}
\ No newline at end of file
diff --git "a/\354\213\240\355\230\234\354\233\220/week5/backjoon_1188.js" "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1188.js"
new file mode 100644
index 0000000..deaf4f1
--- /dev/null
+++ "b/\354\213\240\355\230\234\354\233\220/week5/backjoon_1188.js"
@@ -0,0 +1,16 @@
+const fs = require("fs");
+const input = fs.readFileSync(0, "utf-8").trim().split(" ");
+
+const N = Number(input[0]);
+const M = Number(input[1]);
+
+function gcd(a, b) {
+    while (b !== 0) {
+        let temp = a % b;
+        a = b;
+        b = temp;
+    }
+    return a;
+}
+
+console.log(M - gcd(N, M));
\ No newline at end of file