View Compilation Error

0_0_28456538_22298.cpp: In function 'int main()':
0_0_28456538_22298.cpp:19:31: error: 'slop' was not declared in this scope
    while(L<R&&slop(q[L],q[L+1])<s[i]) L++;//将不可能是最优的解弹出 
                               ^
0_0_28456538_22298.cpp:22:31: error: 'slop' was not declared in this scope
    while(L<R&&slop(q[R-1],q[R])>slop(q[R],i)) R--;
                               ^