/in/foo.cc: In function 'int main()':
/in/foo.cc:15:7: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
     if(i>0)
       ^
/in/foo.cc:19:7: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
     if(i<yushu)
       ^
/in/foo.cc:23:5: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if(b==false&&c==false)
     ^~