View Compilation Error

0_0_15534019_31875.cpp: In function 'int main()':
0_0_15534019_31875.cpp:22:5: error: 'f' was not declared in this scope
     f//reopen("in", "r", stdin);
     ^
0_0_15534019_31875.cpp:23:25: error: 'T' was not declared in this scope
     int T; scanf("%d", &T);
                         ^