Compilare: user.cpp: In function ‘int main()’: user.cpp:68:40: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘long int’ [-Wformat=] fprintf(fopen(OUT, "w"), "%llu\n", sum); ^ user.cpp: In function ‘void read_data()’: user.cpp:23:25: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(IN, "r", stdin); ^