/in/foo.cc: In function 'int main()':
/in/foo.cc:33:3: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   for(;top>1&&cross(B[i]-s[top-1],s[top]-s[top-1])>=0;top--); s[++top]=B[i];
   ^~~
/in/foo.cc:33:63: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
   for(;top>1&&cross(B[i]-s[top-1],s[top]-s[top-1])>=0;top--); s[++top]=B[i];
                                                               ^