books.cpp: In function 'int main()':
books.cpp:29:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
29 | freopen ("task.inp", "r", stdin);
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
books.cpp:30:11: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
30 | freopen ("task.out", "w", stdout);
| ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/cciOXgJX.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccDfdUmY.o:books.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status