Compilare: user.cpp: In function ‘void solve()’: user.cpp:57:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < pos[i].size(); ++ j) ^ user.cpp:69:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == pos[i].size() - 1) ^ user.cpp:79:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < pos[i].size(); ++ j) ^ user.cpp: In function ‘void read()’: user.cpp:35:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:40:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^