diff --git a/058/main.rs b/058/main.rs
index 097fc25..601b412 100644
--- a/058/main.rs
+++ b/058/main.rs
@@ -1,66 +1,102 @@
-struct Step { 
-    i: i8,
-    j: i8
+use std::collections::HashSet;
+
+//  from../ 027/main.rs
+fn er() -> HashSet<u32> {
+    let mut nums = Vec::new();
+    let size = 600_000_000;
+    for _n in 0..size+1 { nums.push(true); }
+    let mut p = 1;
+    loop {
+        let mut found = false;
+        for i in p+1..size {
+            if nums[i] {
+                found = true;
+                p = i;
+                break;
+            }
+        }
+        if !found { break; }
+        for i in (2 * p .. size).step_by(p) {
+            nums[i] = false;
+        }
+    }
+    let mut res = HashSet::new();
+    for i in 2..size {
+        if nums[i] { res.insert(i as u32); }
+    }
+    return res;
 }
 
+
 struct Steps {
     l: usize,
-    i: usize,
-    j: usize,
     k: usize,
     s: usize,
 }
 
 impl Steps {
-    fn new(n: usize) -> Steps {
+    fn new() -> Steps {
         return Steps {
-            i: n / 2,
-            j: n / 2,
             l: 1,
             k: 1,
             s: 0
         };
     }
 
-    fn ads(&mut self, s: &Step) {
-        if s.i < 0 { self.i -= 1; }
-        if s.i > 0 { self.i += 1; }
-        if s.j < 0 { self.j -= 1; }
-        if s.j > 0 { self.j += 1; }
-    }
-
-    fn next(&mut self, n: u32) {
-        //self.corner = false;
-        let mut sts = Vec::new();
-        sts.push(Step { i: 0, j: 1 });
-        sts.push(Step { i: -1, j: 0 });
-        sts.push(Step { i: 0, j: -1 });
-        sts.push(Step { i: 1, j: 0 });
-
+    fn next(&mut self, n: u32) -> Option<u32> {
         if self.k > self.l {
-            //self.corner = true;
             self.k = 1;
             self.s += 1;
-            if self.s == sts.len() {
+            if self.s == 4 {
                 self.s = 0;
                 self.l += 1;
             }
             if self.s == 2 {
                 self.l += 1;
             }
-            println!("{}", n);
         }
-        
-        let st = &sts[self.s];
         self.k += 1;
-        self.ads(st);
+        if self.s == 0 && (self.k - 1 == self.l || self.k == 2) {
+            return Some(n);
+        }
+        if self.s == 2 && self.k == 2 {
+            return Some(n);
+        }
+        if self.s == 3 && self.k == 2 {
+            return Some(n);
+        }
+        return None;
     }
 
 }
 
 fn main() {
-    let mut st = Steps::new(7);
-    for n in 1..20 {
-        st.next(n);
+    let mut st = Steps::new();
+    let ps = er();
+    println!("er");
+    return;
+    let mut sq = 1;
+    let mut corner_count = 0;
+    let mut p_count = 0;
+    for n in 1..900_000_000 {
+        if n > sq * sq {
+            sq += 1;
+        }
+        match st.next(n) {
+            Some(k) => {
+                let is_prime = ps.contains(&k);
+                corner_count += 1;
+                if is_prime {
+                    p_count += 1;
+                }
+
+                let ratio = 100.0 * (p_count as f64) /(corner_count as f64);
+                println!("{}.{} \t({})\t[{}]", k, is_prime, sq, ratio);
+                if ratio < 10.0 {
+                    break;
+                }
+            },
+            None => ()
+        }
     }
 }