Compilare: main.cpp: In function 'int main()': main.cpp:33:64: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("aria.in","r",stdin),freopen("aria.out","w",stdout); ^ main.cpp:33:64: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] main.cpp: In function 'char C()': main.cpp:10:31: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(r,1,M,stdin),e=0; ^