Add multilingual language and systems learning tracks

en/c-foundations-20261101/lesson-3/main.c

@@ -0,0 +1,7 @@
+#include <stdio.h>
+#include <assert.h>
+int remaining(int total, int done) { return done >= total ? 0 : total - done; }
+int main(void) {
+    printf("%d\n", remaining(4, 1));
+    return 0;
+}