Compilare: main.cpp: In function 'bool pairup(int)': main.cpp:17:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i< neighbors[current_node].size() ; ++i) ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:24:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i< neighbors[current_node].size(); ++i) ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:36:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cuplaj.in", "r", stdin); ^ main.cpp:37:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cuplaj.out", "w", stdout); ^ main.cpp:41:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &e); ^ main.cpp:45:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^