View Compilation Error

0_0_16305473_31497.cpp: In function 'int main()':
0_0_16305473_31497.cpp:64:46: error: 'memset' was not declared in this scope
                    memset(mark,0,sizeof(mark));
                                              ^
0_0_16305473_31497.cpp:70:46: error: 'memset' was not declared in this scope
                    memset(mark,0,sizeof(mark));
                                              ^