Compilare: main.cpp: In member function 'void Heap::pushDown(int)': main.cpp:70:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (left < data_.size() && data_[left].val < data_[choice].val) ~~~~~^~~~~~~~~~~~~~ main.cpp:72:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (right < data_.size() && data_[right].val < data_[choice].val) ~~~~~~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:98:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("heapuri.in", "r", stdin); ^ main.cpp:99:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("heapuri.out", "w", stdout); ^ main.cpp:102:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ main.cpp:107:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &op); ^ main.cpp:110:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^ main.cpp:115:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^