Compilare: main.cpp: In function 'int main()': main.cpp:22:15: warning: unused variable 'j' [-Wunused-variable] int n, i, j, top; ^ main.cpp:20:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dag.in", "r", stdin); ^ main.cpp:21:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("dag.out", "w", stdout); ^ main.cpp:24:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:28:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^