init commit

contests/1contest/4.cpp

@@ -0,0 +1,19 @@
+#include <iostream>
+#include <iomanip>
+#include <cmath>
+
+int main() {
+    double tmp, arip = 0, squar = 0;
+    int n = 0;
+    while (std::cin >> tmp) {
+        ++n;
+        arip += (tmp - arip) / n;
+        squar += (tmp * tmp - squar) / n;
+    }
+
+    std::cout << std::setprecision(10);
+
+    std::cout << arip << std::endl << std::sqrt(squar - arip * arip) << std::endl;
+
+    return 0;
+}