Compilare: user.cpp: In function ‘int main()’: user.cpp:23:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0; k + 1 < v[i].size(); k += 2) ^ user.cpp:13:12: warning: unused variable ‘k’ [-Wunused-variable] int n, k, nr, cnt = 0, t; om aux; ^ user.cpp:11:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("wall.in", "r", stdin); ^ user.cpp:12:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("wall.out", "w", stdout); ^ user.cpp:14:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &nr, &n); ^ user.cpp:17:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^