Install yasnippet and vala-snippets packages

elpa/yasnippet-20160924.2001/snippets/cc-mode/main

@@ -0,0 +1,9 @@
+# -*- mode: snippet -*-
+# name: main
+# key: main
+# --
+int main(${1:int argc, char *argv[]})
+{
+    $0
+    return 0;
+}