Compilare: user.cpp: In function ‘int main()’: user.cpp:51:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1 ; i <= n ; ++i) { ^ user.cpp:54:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1 ; j <= m ; ++j) { ^ user.cpp:61:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int l1 = 1 ; l1 <= n ; ++l1) { ^ user.cpp:62:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int l2 = l1 ; l2 <= n ; ++l2) { ^ user.cpp:67:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int col = 1 ; col <= m ; ++col) { ^ user.cpp:41:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("omogene.in" , "r" , stdin); ^ user.cpp:42:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("omogene.out" , "w" , stdout); ^