/in/foo.cc: In function 'bool panduan(int)':
/in/foo.cc:8:38: error: 'm' was not declared in this scope
   a[i]=max(0,v[i]+v[i-1]+v[1]-b[i-1]-m);
                                      ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:20:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   int mid=x+y>>1;
           ~^~