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+# Grammar for Chapter 1
+
+English | [日本語](01-grammar.ja.md)
+
+```antlrv4
+grammar SimpleLanguage;
+
+program
+    : statement EOF
+    ;
+
+statement
+    : 'return' expression ';'
+    ;
+
+expression
+    : primaryExpression
+    ;
+
+primaryExpression
+    : INTEGER_LITERAL
+    ;
+
+INTEGER_LITERAL
+    : [1-9][0-9]*
+    | [0]
+    ;
+```