View Compilation Error

0_0_24860663_32481.cpp: In function 'int main()':
0_0_24860663_32481.cpp:5:30: error: 'scanf' was not declared in this scope
     while(~scanf("%d%d",&x,&y)){
                              ^
0_0_24860663_32481.cpp:6:26: error: 'puts' was not declared in this scope
         if(x>y){puts("-1");continue;}
                          ^
0_0_24860663_32481.cpp:7:41: error: 'printf' was not declared in this scope
         if(x==1||x==y){printf("%d\n",y-1);continue;}
                                         ^
0_0_24860663_32481.cpp:20:26: error: 'printf' was not declared in this scope
         printf("%d\n",ans);
                          ^