triangle.cpp: In function 'void freo(str)':
triangle.cpp:21:26: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
21 | void freo(str x) {freopen((x + ".in").c_str(), "r", stdin);freopen((x + ".out").c_str(), "w", stdout);}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
triangle.cpp:21:67: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
21 | void freo(str x) {freopen((x + ".in").c_str(), "r", stdin);freopen((x + ".out").c_str(), "w", stdout);}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~