View Compilation Error

0_0_18657794_20550.cpp: In function 'int main()':
0_0_18657794_20550.cpp:23:24: error: 'scanf' was not declared in this scope
     while(scanf("%d",&n)!=-1)
                        ^
0_0_18657794_20550.cpp:47:35: error: 'printf' was not declared in this scope
         printf("%f\n",dp[n-1][n-1]);
                                   ^