1 files changed, 1 insertions, 1 deletions

diff --git a/src/day25.cpp b/src/day25.cpp
index aaad9e9..1d5e19e 100644
--- a/src/day25.cpp
+++ b/src/day25.cpp
@@ -79,7 +79,7 @@ random_node(const graph_type& graph)
         static random_device dev;
         static mt19937       generator(dev());
 
-        uniform_int_distribution<graph_type::size_type> distribute(0, graph.size());
+        uniform_int_distribution<graph_type::size_type> distribute(0, graph.size()-1);
 
         auto iter = graph.begin();
         advance(iter, distribute(generator));