prog.cpp:4:5: error: cannot declare ‘::main’ to be a global variable
int main{
^~~~
prog.cpp:5:2: error: expected primary-expression before ‘int’
int n,a,i;
^~~
prog.cpp:5:2: error: expected ‘}’ before ‘int’
prog.cpp:8:2: error: ‘cin’ does not name a type
cin>>n;
^~~
prog.cpp:9:2: error: expected unqualified-id before ‘while’
while(i>n){
^~~~~