Compilare: user.cpp: In function ‘void move_zero(int, int)’: user.cpp:129:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < subway.size(); i++) { ^ user.cpp: In function ‘bool move_element(int, int, int)’: user.cpp:149:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < way.size(); i++) { ^ user.cpp: In function ‘bool move_element_easy(int, int, int)’: user.cpp:188:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 1; i < way.size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:210:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perspico.in", "r", stdin); ^ user.cpp:211:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perspico.out", "w", stdout); ^ user.cpp:213:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:216:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &act[i][j]); ^