Compilare: user.cpp: In function ‘int main()’: user.cpp:135:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < prev.size(); ++i) ^ user.cpp:137:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < nxt.size(); ++i) { ^ user.cpp:79:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.in", "r", stdin); ^ user.cpp:80:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortnet.out", "w", stdout); ^ user.cpp:83:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n", &n, &m); ^ user.cpp:89:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("<%d,%d> ", &xx, &yy); ^