1 files changed, 9 insertions, 0 deletions
diff --git a/4/10.c b/4/10.c
index a57effb..769e606 100644
--- a/4/10.c
+++ b/4/10.c
@@ -24,6 +24,15 @@ void clear();
 int mgetline();
 int getop(char[]);
 
+/* Reverse Polish notation calculator
+      - single uppercase and lowercase characters are variables (syntax 2 A =);
+      - special variable LOUT for the last printed value.
+      - mathematical functions: sin, cos, tan, exp, pow.
+      - custom functions: swp (swap top 2 values), dup (duplicate last value),
+        top (peek at the stack top), cls (clear stack).
+      - operators: +, -, *, /, % and =
+      - press enter to print the value at the top of the stack.
+ */
 int main(int argc, char *argv[]) {
   int type, op1, op2;
   char s[MAXOP];