foo.cpp: In function 'int main()':
foo.cpp:4:5: error: 'longlong' was not declared in this scope
     longlong a,b,t,n;
     ^
foo.cpp:4:14: error: expected ';' before 'a'
     longlong a,b,t,n;
              ^
foo.cpp:5:19: error: 'a' was not declared in this scope
     scanf("%d%d",&a,&b);
                   ^
foo.cpp:5:22: error: 'b' was not declared in this scope
     scanf("%d%d",&a,&b);
                      ^
foo.cpp:8:9: error: 't' was not declared in this scope
         t=a;
         ^
foo.cpp:12:5: error: 'n' was not declared in this scope
     n=a%b;
     ^
foo.cpp:13:5: error: 't' was not declared in this scope
     t=a;
     ^