diff --git a/asdzes2zad1i2eratostenes_mersenne/main.c b/asdzes2zad1i2eratostenes_mersenne/main.c
index a43db00..a7f616f 100644
--- a/asdzes2zad1i2eratostenes_mersenne/main.c
+++ b/asdzes2zad1i2eratostenes_mersenne/main.c
@@ -3,7 +3,7 @@
 
 #pragma pack(push, 1)
 
-#define N 100
+#define N (1 << 10) - 1
 
 struct bool_store {
     int v : 1;
@@ -41,6 +41,20 @@ void doSE()
         }
 }
 
+void do_and_print_mersenne()
+{
+    int p, m, j;
+    for (p = 2; p <= 20; p++) {
+        if (!A_bf2_get(p))
+            continue;
+        m = (1 << p) - 1;
+        for (j = 2; j <= sqrt(m); j++)
+            if (m % j == 0)
+                continue;
+        printf(" 2 ^ %2d - 1 = %6d \n", p, m);
+    }
+}
+
 #define FILL_CHAR '-'
 
 void do_and_print_eratostenes()
@@ -52,8 +66,12 @@ void do_and_print_eratostenes()
             putchar('\n');
         putchar(' ');
         if (A_bf2_get(i))
-            printf(" %2d", i);
+            printf("%4d", i);
         else {
+            if (i >= 1000)
+                putchar(FILL_CHAR);
+            else
+                putchar(' ');
             if (i >= 100)
                 putchar(FILL_CHAR);
             else
@@ -68,10 +86,6 @@ void do_and_print_eratostenes()
     putchar('\n');
 }
 
-void do_and_print_mersenne()
-{
-}
-
 int main()
 {
     do_and_print_eratostenes();