Compilare: user.cpp: In function ‘int main()’: user.cpp:51:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < cells.size(); ++ i) { ^ user.cpp:35:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.in", "r", stdin); ^ user.cpp:36:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.out", "w", stdout); ^ user.cpp:39:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:43:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i][j]); ^ user.cpp:70:24: warning: ‘wherey’ may be used uninitialized in this function [-Wmaybe-uninitialized] dfs(wherex, wherey); ^ user.cpp:70:24: warning: ‘wherex’ may be used uninitialized in this function [-Wmaybe-uninitialized]