View Compilation Error

0_0_21296829_24888.cpp: In function 'int KM()':
0_0_21296829_24888.cpp:31:32: error: 'memset' was not declared in this scope
 memset(linker,-1,sizeof(linker));
                                ^
0_0_21296829_24888.cpp: In function 'int main()':
0_0_21296829_24888.cpp:73:20: error: 'scanf' was not declared in this scope
 while(scanf("%d",&n) == 1)
                    ^
0_0_21296829_24888.cpp:79:19: error: 'printf' was not declared in this scope
 printf("%d\n",KM());
                   ^
0_0_21296829_24888.cpp:81:9: error: expected '}' at end of input
 return 0;
         ^