View Compilation Error

0_0_30852890_27003.cpp: In function 'int main()':
0_0_30852890_27003.cpp:24:16: error: 'ans' was not declared in this scope
    if(!G[i][j])ans++;
                ^
0_0_30852890_27003.cpp:37:2: error: 'ans' was not declared in this scope
  ans -= d[n];
  ^