art.cpp: In function 'void usaco(std::string)':
art.cpp:6:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
6 | void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
art.cpp:6:66: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
6 | void usaco(string s){freopen((s+".in").c_str(),"r",stdin);freopen((s+".out").c_str(),"w",stdout);}
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
art.cpp: In function 'int main()':
art.cpp:21:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
21 | scanf("%d",&n);
| ~~~~~^~~~~~~~~
art.cpp:22:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
22 | for(int i=1;i<=n;i++)scanf("%lld%lld",&p[i].fr,&p[i].sc);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~