Compilare: user.cpp: In function ‘int main()’: user.cpp:130:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < wh[gr].size(); i++) { ^ user.cpp:108:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tower8.in","r",stdin); ^ user.cpp:109:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tower8.out","w",stdout); ^ user.cpp:111:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:114:64: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &mat[i][j]), wh[mat[i][j]].pb(mp(i, j)); ^