Compilare: user.cpp: In function ‘int main()’: user.cpp:108:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < on_line[i].size(); j++) { ^ user.cpp:111:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j + 1 < on_line[i].size()) ^ user.cpp:73:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tramvai.in","r",stdin); ^ user.cpp:74:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tramvai.out","w",stdout); ^ user.cpp:76:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:78:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &xx1, &yy1, &xx2, &yy2); ^ user.cpp:81:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &ls1, &ls2, &lf1, &lf2); ^