View Compilation Error

0_0_30342851_19149.cpp: In function 'int main()':
0_0_30342851_19149.cpp:6:22: error: 'scanf' was not declared in this scope
  while(~scanf("%d",&T))
                      ^
0_0_30342851_19149.cpp:11:43: error: 'strlen' was not declared in this scope
    int a[25]={0},t=1,ans=0,ii,len=strlen(s);
                                           ^
0_0_30342851_19149.cpp:36:31: error: 'printf' was not declared in this scope
    printf("%d\n",ans^(len&1)^1);
                               ^