非负数。
inline void In(int& res) { int c; while((c = getchar())<'0' || c>'9'); res = c-'0'; while((c = getchar())>='0' && c<='9') res = res*10 + c-'0'; }
有负数。
inline void In(int& res) { int f=1,c; while(((c = getchar())<'0' || c>'9') && c!='-'); c=='-' ? f=res=0 : res=c-'0'; while((c = getchar())>='0' && c<='9') res = res*10 + c-'0'; if(!f) res=-res; }