Compilare: main.cpp: In function 'int main()': main.cpp:60:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < edges[t.target].size(); i++) ~~^~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:19:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ninjago.in", "r", stdin); ^ main.cpp:20:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ninjago.out", "w", stdout); ^