Compilare: user.cpp: In function ‘int main()’: user.cpp:172:9: warning: unused variable ‘a’ [-Wunused-variable] int a, b, c; ^ user.cpp:172:12: warning: unused variable ‘b’ [-Wunused-variable] int a, b, c; ^ user.cpp:172:15: warning: unused variable ‘c’ [-Wunused-variable] int a, b, c; ^ user.cpp:162:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("algola.in", "r", stdin); ^ user.cpp:163:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("algola.out", "w", stdout); ^