View Compilation Error

0_0_19031103_16100.cpp: In function 'int main()':
0_0_19031103_16100.cpp:8:17: error: 'gets' was not declared in this scope
     while(gets(a) && a[0]!='0')
                 ^
0_0_19031103_16100.cpp:17:20: error: 'printf' was not declared in this scope
     printf("%d\n",n) ;
                    ^
0_0_19031103_16100.cpp:31:25: error: 'printf' was not declared in this scope
        printf("%d\n",sum) ;
                         ^