View Compilation Error

0_0_38289516_13576.cpp: In function 'int main()':
0_0_38289516_13576.cpp:37:30: error: 'strlen' was not declared in this scope
             int kaka=strlen(H);
                              ^
0_0_38289516_13576.cpp:61:31: error: 'sort' was not declared in this scope
             sort(a+1,a+n+1,cmp);
                               ^