Compilare: user.cpp: In function ‘int main()’: user.cpp:33:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(M.size() > K) break; ^ user.cpp:14:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("submatrix.in","r",stdin); ^ user.cpp:15:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("submatrix.out","w",stdout); ^ user.cpp:17:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&n,&m,&K); ^ user.cpp:20:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&A[i][j]); ^