Added problem 584B from codeforces

Author: jhonber

codeforces/Codeforces Round #324 (Div. 2)/B.cpp

@@ -0,0 +1,26 @@
+// http://codeforces.com/contest/584/problem/B
+
+#include<bits/stdc++.h>
+using namespace std;
+
+long long md = 1e9 + 7;
+
+long long mpow (long long a, long long b) {
+  long long p = a;
+  while (b --> 1) {
+    p = (p * a) % md;
+    p %= md;
+  }
+
+  return p % md;
+}
+
+int main() {
+  int n;
+  cin >> n;
+
+  long long a = mpow(3LL, n * 3);
+  long long b = mpow(7LL, n);
+  long long tmp = (a + md) - b;
+  cout << tmp % md;
+}

codeforces/data.db

@@ -677,4 +677,5 @@
 13425589
 13463792
 13443199
-13465613
+13465613
+13486876