/in/foo.cc: In function 'int Pushup(int)':
/in/foo.cc:11:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int Pushdown(int, int)':
/in/foo.cc:31:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int build(int, int, int)':
/in/foo.cc:20:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int updata(int, int, int, int, int, int)':
/in/foo.cc:45:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^