Compilare: user.cpp: In function ‘int main()’: user.cpp:41:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("coprime.in", "r", stdin); ^ user.cpp:42:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("coprime.out", "w", stdout); ^ user.cpp:43:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(scanf("%d %d", &n, &m); m; --m) scanf("%d %d", &i, &j), edg[i][j] = edg[j][i] = 1; ^ user.cpp:43:88: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(scanf("%d %d", &n, &m); m; --m) scanf("%d %d", &i, &j), edg[i][j] = edg[j][i] = 1; ^