diff --git a/latex_src/little_languages.tex b/latex_src/little_languages.tex
index 39afc37..291bda1 100644
--- a/latex_src/little_languages.tex
+++ b/latex_src/little_languages.tex
@@ -690,7 +690,7 @@ \section{逆波兰式计算器}
                 top = 0
                 next
             }
-        if (top == 1)
+        if (top == 1 && i == NF)
             printf("\t%.8g\n", stack[top--])
         else if (top > 1) {
             printf("error: too many operands\n")
@@ -729,7 +729,7 @@ \section{逆波兰式计算器}
 
     { for (i = 1; i <= NF; i++)
           if ($i ~ /^[+-]?([0-9]+[.]?[0-9]*|[.][0-9]+)$/) {
-              stack[++top] = $i
+              stack[++top] = $i 
           } else if ($i == "+" && top > 1) {
               stack[top-1] += stack[top]; top--
           } else if ($i == "-" && top > 1) {
@@ -763,7 +763,7 @@ \section{逆波兰式计算器}
               top = 0
               next
           }
-      if (top == 1 && $NF !~ /\=$/)
+      if (top == 1 && i == NF && $NF !~ /\=$/)
           printf("\t%.8g\n", stack[top--])
       else if (top > 1) {
           printf("error: too many operands\n")