Compilare: main.cpp: In function 'int main()': main.cpp:125:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < leftNodes.size(); ++i) { ~~^~~~~~~~~~~~~~~~~~ main.cpp:93:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("atac2.in", "r", stdin); ^ main.cpp:94:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("atac2.out", "w", stdout); ^