Compilare: main.cpp: In function 'int main()': main.cpp:60:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; sol.size() < n - 1; i++) ~~~~~~~~~~~^~~~~~~ main.cpp:47:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in", "r", stdin); ^ main.cpp:48:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out", "w", stdout); ^ main.cpp:51:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:53:54: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &v[i].x, &v[i].y, &v[i].cost); ^