Compilare: user.cpp: In function ‘int main()’: user.cpp:56:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int a = 0, b = 0; a < v[1][i].size () && b < v[2][i].size ();) ^ user.cpp:56:73: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int a = 0, b = 0; a < v[1][i].size () && b < v[2][i].size ();) ^ user.cpp:59:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (a < v[1][i].size () && v[1][i][a] < v[2][i][b]) ^ user.cpp:78:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] } while (b < v[2][i].size () && v[2][i][b] < v[1][i][a]); ^ user.cpp:22:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("stalpi3.in", "r", stdin); ^ user.cpp:23:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("stalpi3.out", "w", stdout); ^ user.cpp:26:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &n, &d); ^ user.cpp:32:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &x, &y); ^ user.cpp:43:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &x, &y); ^