Compilare: user.cpp: In function ‘int main()’: user.cpp:28:9: warning: unused variable ‘a’ [-Wunused-variable] int a, b, c, i, j; ^ user.cpp:28:12: warning: unused variable ‘b’ [-Wunused-variable] int a, b, c, i, j; ^ user.cpp:28:15: warning: unused variable ‘c’ [-Wunused-variable] int a, b, c, i, j; ^ user.cpp:28:21: warning: unused variable ‘j’ [-Wunused-variable] int a, b, c, i, j; ^ user.cpp:26:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tg.in", "r", stdin); ^ user.cpp:27:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tg.out", "w", stdout); ^ user.cpp:30:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^