Compilare: user.cpp: In function ‘int main()’: user.cpp:30:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( j = 0 ; j < v[i].size() ; ++ j ) ^ user.cpp:12:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "lupu.in", "r", stdin ); ^ user.cpp:13:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "lupu.out", "w", stdout ); ^ user.cpp:16:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d%d%d", &n, &x, &l ); ^ user.cpp:18:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%d%d", &d, &a ); ^