Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:17:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < l[x].size(); ++i) ^ user.cpp:25:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < l[x].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:95:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < chain[i].size(); ++j){ ^ user.cpp:81:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavypath.in", "r", stdin); ^ user.cpp:82:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavypath.out", "w", stdout); ^ user.cpp:83:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:85:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^ user.cpp:87:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^ user.cpp:104:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &t, &x, &y); ^