View Compilation Error

0_0_31129639_2645.cpp: In function 'void topo()':
0_0_31129639_2645.cpp:46:24: error: 'N' was not declared in this scope
  for ( int i = 1; i <= N; i++ ) {
                        ^
0_0_31129639_2645.cpp:52:7: error: 'cnt' was not declared in this scope
   ans[cnt++] = u;
       ^
0_0_31129639_2645.cpp:53:25: error: 'N' was not declared in this scope
   for ( int v = 1; v <= N; v++ ) {
                         ^
0_0_31129639_2645.cpp:54:9: error: 'graph' was not declared in this scope
    if ( graph[u][v] ) {
         ^
0_0_31129639_2645.cpp:60:23: error: 'cnt' was not declared in this scope
  for ( int i = 0; i < cnt; i++ ) {
                       ^