diff --git a/2023/07/04-sum-in-a-matrix.rs b/2023/07/04-sum-in-a-matrix.rs
new file mode 100644
index 0000000..c1c925a
--- /dev/null
+++ b/2023/07/04-sum-in-a-matrix.rs
@@ -0,0 +1,8 @@
+impl Solution {
+    pub fn matrix_sum(mut nums: Vec<Vec<i32>>) -> i32 {
+        nums.iter_mut().for_each(|row| row.sort());
+        (0..nums[0].len())
+            .map(|i| nums.iter().map(|row| row[i]).max().unwrap())
+            .sum()
+    }
+}