diff --git "a/junhuikim/2869-\353\213\254\355\214\275\354\235\264\353\212\224\354\230\254\353\235\274\352\260\200\352\263\240\354\213\266\353\213\244.cpp" "b/junhuikim/2869-\353\213\254\355\214\275\354\235\264\353\212\224\354\230\254\353\235\274\352\260\200\352\263\240\354\213\266\353\213\244.cpp"
new file mode 100644
index 0000000..7a1cca6
--- /dev/null
+++ "b/junhuikim/2869-\353\213\254\355\214\275\354\235\264\353\212\224\354\230\254\353\235\274\352\260\200\352\263\240\354\213\266\353\213\244.cpp"
@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <iostream>
+
+using namespace std;
+
+int main(void) {
+    int A, B, V;
+
+    scanf("%d %d %d", &A, &B, &V);
+
+    int todo = V-A;
+    int dV = A-B;
+
+    int day = 1;
+
+    if(todo % dV == 0) {
+        day += todo/dV;
+    } else {
+        day += todo/dV + 1;
+
+    }
+
+    printf("%d", day);
+}
\ No newline at end of file
diff --git a/junhuikim/rootN.cpp b/junhuikim/rootN.cpp
new file mode 100644
index 0000000..6ed6d3e
--- /dev/null
+++ b/junhuikim/rootN.cpp
@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <iostream>
+
+using namespace std;
+
+// This calculates root N.
+// After starting this program, put the N you want.
+int main(void) {
+    double N;
+
+    double start, mid, end;
+
+    double result;
+
+    scanf("%lf", &N);
+
+    start = 0;
+    end = N;
+
+    mid = (start + end) / 2;
+
+    for (int i = 0; i < 100; i++) {
+        result = mid * mid;
+
+        if (result == N) {
+            break;
+        }
+
+        if (result > N) {
+            end = mid;
+        }
+
+        if (result < N) {
+            start = mid;
+        }
+
+        mid = (start + end) / 2;
+    }
+
+    printf("%lf", mid);
+    return 0;
+}
\ No newline at end of file