diff --git a/src/include/main.h b/src/include/main.h
index e69de29..5d4df47 100644
--- a/src/include/main.h
+++ b/src/include/main.h
@@ -0,0 +1,7 @@
+#ifndef MAIN_H
+#define MAIN_H
+
+void die(char *, ...);
+void free_s(void *);
+
+#endif
diff --git a/src/include/segment.h b/src/include/segment.h
index e69de29..f1893d2 100644
--- a/src/include/segment.h
+++ b/src/include/segment.h
@@ -0,0 +1,16 @@
+#ifndef SEGMENT_H
+#define SEGMENT_H
+
+typedef struct segment_T {
+    int x;
+    int y;
+    int prev_x;
+    int prev_y;
+} Segment;
+
+Segment *new_segment(int, int);
+void delete_segment(Segment *);
+
+void segment_move(Segment *, int, int);
+
+#endif
diff --git a/src/include/snake.h b/src/include/snake.h
index e69de29..85100a6 100644
--- a/src/include/snake.h
+++ b/src/include/snake.h
@@ -0,0 +1,23 @@
+#ifndef SNAKE_H
+#define SNAKE_H
+
+enum dirn {
+    UP = 0,
+    DOWN,
+    RIGHT,
+    LEFT
+};
+
+typedef struct snake_T {
+    Segments **n;
+    size_t len;
+    int head_dirn;
+} Snake;
+
+Snake *new_snake(size_t, int, int, int);
+void *delete_snake(Snake *);
+
+void snake_forward(Snake *, int);
+int snake_eat(Snake *);
+
+#endif
diff --git a/src/main.c b/src/main.c
index 9125daa..0fb6ee0 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,4 +1,22 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdarg.h>
 
 #include "include/main.h"
+
+void die(char *fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+
+    fprintf(stderr, "fatal: ");
+    vfprintf(stderr, fmt, args);
+    fprintf(stderr, "\n");
+
+    va_end(args)
+    exit(1);
+}
+
+void free_s(void *p) {
+    free(p);
+    p = NULL;
+}
diff --git a/src/segment.c b/src/segment.c
index e69de29..366bcc0 100644
--- a/src/segment.c
+++ b/src/segment.c
@@ -0,0 +1,31 @@
+#include <stdlib.h>
+
+#include "include/main.h"
+#include "include/segment.h"
+
+Segment *new_segment(int x, int y) {
+    Segment c;
+    c = (Segment *)malloc(sizeof(Segment));
+    if (!c)
+        die("segment.c: new_segment(): 'c' is null pointer");
+
+    c->x = x;
+    c->y = y;
+    c->prev_x = EOF;
+    c->prev_y = EOF;
+
+    return c;
+}
+void delete_segment(Segment *c) {
+    free_s(c);
+}
+
+void segment_move(Segment *c, int x, int y) {
+    if (!c)
+        die("segment.c: segment_move(): 'c' is null pointer");
+
+    c->prev_x = c->x;
+    c->x = x;
+    c->prev_y = c->y;
+    c->y = y;
+}
diff --git a/src/snake.c b/src/snake.c
index e69de29..8084b61 100644
--- a/src/snake.c
+++ b/src/snake.c
@@ -0,0 +1,23 @@
+#include <stdlib.h>
+
+#include "include/main.h"
+#include "include/segment.h"
+#include "include/snake.h"
+
+Snake *new_snake(size_t len, int head_dirn, int x, int y) {
+    Snake *s;
+    s = (Snake *)malloc(sizeof(Snake));
+    if (!s)
+        die("snake.c: new_snake(): 's' is null pointer");
+
+    s->n = (Segment **)malloc(sizeof(Segment *) * len);
+    if (!s->n)
+        die("snake.c: new_snake(): 's->n' is null pointer");
+    for (size_t i = 0; i < len; i++) {
+        s->*n[i] = new_segment(x, y--);
+    }
+}
+void *delete_snake(Snake *);
+
+void snake_forward(Snake *, int);
+int snake_eat(Snake *);