View Compilation Error

0_0_17064992_23702.cpp: In function 'int main()':
0_0_17064992_23702.cpp:6:27: error: 'scanf' was not declared in this scope
     while(scanf("%c",&s[0])!=EOF)
                           ^
0_0_17064992_23702.cpp:6:30: error: 'EOF' was not declared in this scope
     while(scanf("%c",&s[0])!=EOF)
                              ^
0_0_17064992_23702.cpp:19:24: error: 'printf' was not declared in this scope
         printf("%d\n",a);
                        ^