Main.cpp: In function 'void file()':
Main.cpp:18:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
18 | freopen("input.txt.txt","r",stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:19:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
19 | freopen("output.txt.txt","w",stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp: In function 'void file(std::string)':
Main.cpp:22:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
22 | freopen((s + ".in").c_str(), "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:23:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
23 | freopen((s + ".out").c_str(), "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp: At global scope:
Main.cpp:15:12: warning: 'called' defined but not used [-Wunused-variable]
15 | static int called = 0;const long long MOD = 1e9+7; // 1e9 + 7
| ^~~~~~