foo.cpp:4:25: error: size of array 'graph' is too large
 int graph[300000][300000];
                         ^
foo.cpp: In function 'void cover(int, int, int, int, int, int)':
foo.cpp:8:10: error: invalid types 'int[int]' for array subscript
   graph[i][j]=tot;
          ^
foo.cpp: In function 'int main()':
foo.cpp:14:9: error: 'graph' was not declared in this scope
  memset(graph,0,sizeof(graph));
         ^
foo.cpp:17:12: warning: right operand of comma operator has no effect [-Wunused-value]
   cin>>a,b,g,k;
            ^
foo.cpp:17:14: warning: right operand of comma operator has no effect [-Wunused-value]
   cin>>a,b,g,k;
              ^
foo.cpp:17:15: warning: right operand of comma operator has no effect [-Wunused-value]
   cin>>a,b,g,k;
               ^
foo.cpp:20:7: error: 'x' was not declared in this scope
  cin>>x>>y;
       ^
foo.cpp:20:10: error: 'y' was not declared in this scope
  cin>>x>>y;
          ^