foo.cc: In function 'long long int Solve(long long int, long long int, long long int, long long int)':
foo.cc:100:12: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (a > 0 && d < 0 || a<0 && d>0) //a,d异号
      ~~~~~~^~~~~~~~
foo.cc:108:12: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if (b > 0 && c < 0 || b<0 && c>0) //b,c异号
      ~~~~~~^~~~~~~~
foo.cc:142:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

[Hydro](https://hydro.ac)提供评测服务