Compilare: user.cpp: In function ‘int main()’: user.cpp:40:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("taxa.out","w",stdout); ^ user.cpp:41:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("taxa.in","r",stdin); ^ user.cpp:42:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d%d%d",&N,&M,&p1.a,&p1.b,&p2.a,&p2.b); ^ user.cpp:45:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&d[i][j]), c[i][j] = -1; ^