magnus.cpp: In function 'int main()':
magnus.cpp:36:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
36 | for(int i=0; i<s.size(); i++){
| ~^~~~~~~~~
magnus.cpp: In function 'void f()':
magnus.cpp:9:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
9 | freopen("in.txt", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
magnus.cpp:10:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
10 | freopen("out.txt", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~