View Compilation Error

0_0_18434863_2794.cpp: In function 'int main()':
0_0_18434863_2794.cpp:194:42: error: 'reverse' was not declared in this scope
           reverse(ssub.begin(),ssub.end());
                                          ^
0_0_18434863_2794.cpp:199:44: error: 'reverse' was not declared in this scope
           reverse(ssub1.begin(),ssub1.end());
                                            ^