View Compilation Error

0_0_37536768_21596.cpp: In function 'int main()':
0_0_37536768_21596.cpp:5:1: error: expected initializer before 'int'
 int a,b;
 ^
0_0_37536768_21596.cpp:6:19: error: 'n' was not declared in this scope
 while(scanf("%d",&n)==1){
                   ^
0_0_37536768_21596.cpp:11:15: error: 'a' was not declared in this scope
 scanf("%d%d",&a);
               ^