View Compilation Error

0_0_21440481_3467.cpp: In function 'int main()':
0_0_21440481_3467.cpp:7:18: error: 'scanf' was not declared in this scope
     scanf("%d",&t);
                  ^
0_0_21440481_3467.cpp:20:37: error: 'changesame' was not declared in this scope
             changesame(a,b,l[j],r[j]);
                                     ^
0_0_21440481_3467.cpp:23:27: error: 'printf' was not declared in this scope
             printf("Yes\n");
                           ^
0_0_21440481_3467.cpp:25:26: error: 'printf' was not declared in this scope
             printf("No\n");
                          ^