Compilare: user.cpp: In function ‘void solve()’: user.cpp:144:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<=max(in.size(), out.size()); ++i){ ^ user.cpp: In function ‘void read()’: user.cpp:34:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("plan.in", "r", stdin); ^ user.cpp:35:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("plan.out", "w", stdout); ^ user.cpp:37:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.cpp:41:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &from, &to); ^