View Compilation Error

0_0_18068543_30237.cpp: In function 'int main()':
0_0_18068543_30237.cpp:4:21: error: 'scanf' was not declared in this scope
  while(scanf("%d",&n) != EOF)
                     ^
0_0_18068543_30237.cpp:4:26: error: 'EOF' was not declared in this scope
  while(scanf("%d",&n) != EOF)
                          ^
0_0_18068543_30237.cpp:9:16: error: 'a' was not declared in this scope
    scanf("%d",&a[i]);
                ^
0_0_18068543_30237.cpp:12:7: error: 'a' was not declared in this scope
    if(a[i]<0)
       ^
0_0_18068543_30237.cpp:54:22: error: 'printf' was not declared in this scope
    printf("%d\n",step);
                      ^
0_0_18068543_30237.cpp:56:22: error: 'printf' was not declared in this scope
    printf("Endless\n");
                      ^