diff --git a/6.0s1.h b/6.0s1.h
index 597d5fc..67986e9 100644
--- a/6.0s1.h
+++ b/6.0s1.h
@@ -6,10 +6,10 @@ struct s1_location {
     int line;
 };
 
-typedef int       S1_INT;
-typedef long long S1_LONG;
-typedef double    S1_DOUBLE;
-typedef char      S1_CHAR;
+typedef int       s1_int;
+typedef long long s1_long;
+typedef double    s1_double;
+typedef char      s1_char;
 
 
 #define S1_LOC() (struct s1_location){__FILE__, __LINE__}
@@ -36,22 +36,22 @@ void s1_trace(const char *text, struct s1_location loc) {
 
 // 2. simple IO
 
-void write_int(S1_INT value, struct s1_location loc) {
+void write_int(s1_int value, struct s1_location loc) {
     int rc = printf("%d", value);
     s1_assert(rc != EOF, "Error: write_int", loc);
 }
 
-void write_long(S1_LONG value, struct s1_location loc) {
+void write_long(s1_long value, struct s1_location loc) {
     int rc = printf("%lld", value);
     s1_assert(rc != EOF, "Error: write_long", loc);
 }
 
-void write_double(S1_DOUBLE value, struct s1_location loc) {
+void write_double(s1_double value, struct s1_location loc) {
     int rc = printf("%lf", value);
     s1_assert(rc != EOF, "Error: write_long", loc);
 }
 
-void write_char(S1_CHAR value, struct s1_location loc) {
+void write_char(s1_char value, struct s1_location loc) {
     int rc = printf("%c", value);
     s1_assert(rc != EOF, "Error: write_char", loc);
 }
@@ -61,36 +61,36 @@ void write_char(S1_CHAR value, struct s1_location loc) {
 #define write_double(value)   write_double(value, S1_LOC())
 #define write_char(value)     write_char(value, S1_LOC())
 
-S1_INT read_int(struct s1_location loc) {
-    S1_INT value = 0;
+s1_int read_int(struct s1_location loc) {
+    s1_int value = 0;
     int rc = scanf("%d", &value);
     s1_assert(rc == 1, "Error: read_int", loc);
     return value;
 }
 
-S1_LONG read_long(struct s1_location loc) {
-    S1_LONG value = 0;
+s1_long read_long(struct s1_location loc) {
+    s1_long value = 0;
     int rc = scanf("%lld", &value);
     s1_assert(rc == 1, "Error: read_long", loc);
     return value;
 }
 
-S1_DOUBLE read_double(struct s1_location loc) {
-    S1_DOUBLE value = 0.0;
+s1_double read_double(struct s1_location loc) {
+    s1_double value = 0.0;
     int rc = scanf("%lf", &value);
     s1_assert(rc == 1, "Error: read_double", loc);
     return value;
 }
 
-S1_CHAR read_char(struct s1_location loc) {
-    S1_CHAR value = 0;
+s1_char read_char(struct s1_location loc) {
+    s1_char value = 0;
     int rc = scanf("%c", &value);
     s1_assert(rc == 1, "Error: read_char", loc);
     return value;
 }
 
 void read_pnl(struct s1_location loc) {
-    S1_CHAR value = 0;
+    s1_char value = 0;
     while (1) {
         int rc = scanf("%c", &value);
         if (feof(stdin)) {