Compilare: main.cpp: In function 'int main()': main.cpp:65:17: warning: unused variable 'val' [-Wunused-variable] int val = l[i].top(); ^~~ main.cpp:22:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("triaj.in", "r", stdin); ^ main.cpp:23:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("triaj.out", "w", stdout); ^ main.cpp:25:20: 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", &a[i]); ^