diff --git a/Makefile b/Makefile
index f2852bf..dce53f3 100644
--- a/Makefile
+++ b/Makefile
@@ -7,6 +7,8 @@ C_OPT_FLAGS?=
 CXX_OPT_FLAGS?= -felide-constructors
 LD_OPT_FLAGS?=-O3 -flto
 
+INCLUDE=$(shell pwd)/common/include
+
 COMMON_FLAGS=-Wall -pedantic $(COMMON_OPT_FLAGS)
 
 CFLAGS+=$(COMMON_FLAGS) --std=gnu11 $(C_OPT_FLAGS)
@@ -15,7 +17,7 @@ LDFLAGS+=$(LD_OPT_FLAGS)
 
 DAYS= $(wildcard day*)
 
-ENV= CFLAGS="$(CFLAGS)" CXXFLAGS="$(CXXFLAGS)" LDFLAGS="$(LDFLAGS)"
+ENV= CFLAGS="$(CFLAGS)" CXXFLAGS="$(CXXFLAGS)" LDFLAGS="$(LDFLAGS)" INCLUDE="$(INCLUDE)"
 
 .PHONY: all
 
diff --git a/common/include/attrs.h b/common/include/attrs.h
new file mode 100644
index 0000000..f1bcda7
--- /dev/null
+++ b/common/include/attrs.h
@@ -0,0 +1,19 @@
+#ifndef _ATTRS_H
+#define _ATTRS_H
+
+#define pure __attribute__((pure))
+#define noglobal __attribute__((const))
+#define noinline __attribute__((noinline))
+#define cold __attribute__((cold))
+
+#ifndef DEBUG
+#define _force_inline __attribute__((gnu_inline)) inline extern
+#else
+#define _force_inline __attribute__((gnu_inline)) inline static
+#endif
+
+#ifndef __cplusplus // sepples has [[noreturn]]
+#define noreturn __attribute__((noreturn)) void
+#endif
+
+#endif /* _ATTRS_H */
diff --git a/common/include/panic.h b/common/include/panic.h
new file mode 100644
index 0000000..968ab1d
--- /dev/null
+++ b/common/include/panic.h
@@ -0,0 +1,24 @@
+#ifndef _PANIC_H
+#define _PANIC_H
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+#include "attrs.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wall"
+noinline cold static noreturn panic(const char* msg, ...)
+{
+	va_list va;
+	va_start(va, msg);
+	fputs("Fatal error: ", stderr);
+	vfprintf(stderr, msg, va);
+	va_end(va);
+	fputs("\n", stderr);
+	abort();
+}
+#pragma GCC diagnostic pop
+
+#endif /* _PANIC_H */
diff --git a/day6/Makefile b/day6/Makefile
index 7eb034d..65b8d9c 100644
--- a/day6/Makefile
+++ b/day6/Makefile
@@ -7,10 +7,12 @@ OPT_FLAGS?= -O3 -march=native -pipe -flto \
 CFLAGS?=$(OPT_FLAGS)
 LDFLAGS?=-O3 -flto
 
-CFLAGS+= -Wall -pedantic --std=gnu11 
+INCLUDE?=../common/include
+
+CFLAGS+= -Wall -Wextra -Wstrict-aliasing -pedantic --std=gnu11 -I$(INCLUDE)
 
 .PHONY: all
-all: part1 
+all: part1 part2 
 
 inpu%.h: inpu%
 	@rm -f $@
diff --git a/day6/day6.c b/day6/day6.c
index 1173274..a6701a9 100644
--- a/day6/day6.c
+++ b/day6/day6.c
@@ -8,6 +8,9 @@
 #define DEBUG
 #endif
 
+#include <attrs.h>
+#include <panic.h>
+
 static const char* const answers[] = {
 #ifdef TEST
 #include "input-test.h"
@@ -31,12 +34,11 @@ typedef struct answer
 	 table[NUM_QUESTIONS];
 } answers_t;
 
-inline static char assert_in_bound(char i)
+noglobal inline static char assert_in_bound(char i)
 {
 	register int x=(int)i;
 	if(x<0 || x>=NUM_QUESTIONS) {
-		fprintf(stderr, "Fatal error: char '%c' (%d) is not in range 0..%d\n", i, x, NUM_QUESTIONS);
-		abort();
+		panic("char '%c' (%d) is not in range 0..%d", i, x, NUM_QUESTIONS);
 	}
 	return i;
 }
@@ -53,7 +55,7 @@ static void populate(const char* from, answers_t * restrict ans) //wtf is this s
 								1;
 }
 
-static size_t count_ans(const answers_t* restrict ans) 
+pure static size_t count_ans(const answers_t* restrict ans) 
 {
 	register size_t j=0;
 	for(register size_t i=0;i<NUM_QUESTIONS;i++)