Compilare: main.cpp: In function 'int main()': main.cpp:19:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sahara.in","r",stdin); ^ main.cpp:20:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sahara.out","w",stdout); ^ main.cpp:24:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&m,&q,&t); ^ main.cpp:27:50: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d%d",&x1,&y1,&x2,&y2,&cost); ^