Compilare: main.cpp: In function 'int main()': main.cpp:41:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0; k<arcs[j].size(); ++k) ~^~~~~~~~~~~~~~~ main.cpp:49:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<arcs[0].size(); ++i) { ~^~~~~~~~~~~~~~~ main.cpp:15:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.in", "r", stdin); ^ main.cpp:16:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("hamilton.out", "w", stdout); ^ main.cpp:19:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:31:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &x, &y, &co); ^