Compilare: main.cpp:2:0: warning: ignoring #pragma gcc optimize [-Wunknown-pragmas] #pragma gcc optimize("O3") main.cpp: In function 'int main()': main.cpp:134:15: warning: unused variable 'ans' [-Wunused-variable] long long ans = 0; ^~~ main.cpp: In member function 'char InParser::read_ch()': main.cpp:14:29: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^