View Compilation Error

0_0_31393889_7665.cpp: In function 'int main()':
0_0_31393889_7665.cpp:14:27: error: 'memset' was not declared in this scope
   memset(cnt,0,sizeof(cnt)) ; 
                           ^
0_0_31393889_7665.cpp:25:4: error: 'cin' was not declared in this scope
    cin >> l >> r ; 
    ^