View Compilation Error

0_0_26520845_5283.cpp: In function 'int main()':
0_0_26520845_5283.cpp:3:9: error: 'eof' was not declared in this scope
         eof notice { if(n%2==0) sum=n/2*(1+n); else sum = (1+n)/2*n; printf("%d\n\n",sum); } return 0; }
         ^