diff --git a/Cargo.lock b/Cargo.lock
index 7baa389..f25a28a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5,3 +5,12 @@ version = 3
 [[package]]
 name = "aoc2021"
 version = "0.1.0"
+dependencies = [
+ "bounded-vec-deque",
+]
+
+[[package]]
+name = "bounded-vec-deque"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2225b558afc76c596898f5f1b3fc35cfce0eb1b13635cbd7d1b2a7177dc10ccd"
diff --git a/Cargo.toml b/Cargo.toml
index a028c28..b6ab0e5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+bounded-vec-deque = "0.1.1"
diff --git a/src/main.rs b/src/main.rs
index 55dbcb5..afa12de 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,20 +3,28 @@ use std::io::prelude::*;
 use std::env;
 use std::fs::File;
 
+use bounded_vec_deque::BoundedVecDeque;
+
 
 fn main() -> io::Result<()> {
     let args: Vec<String> = env::args().collect();
     let f = File::open(&args[1])?;
     let buf = io::BufReader::new(f);
+    let mut deque: BoundedVecDeque<i32> = BoundedVecDeque::with_capacity(3, 3);
     let mut last = -1;
     let mut count_incr = 0;
     for line in buf.lines() {
         if let Ok(l) = line {
             if let Ok(value) = i32::from_str_radix(&l, 10) {
-                if last > 0 && value > last {
+                deque.push_back(value);
+            }
+            if deque.is_full() {
+                eprintln!("{:?}", deque);
+                let sum = deque.iter().sum();
+                if last > -1 && sum > last {
                     count_incr += 1;
                 }
-                last = value;
+                last = sum;
             }
         }
     }