View Compilation Error

0_0_37348807_24161.cpp: In function 'int main()':
0_0_37348807_24161.cpp:30:51: error: 'x' was not declared in this scope
    while(idx<n && a[idx].x>=b[i].x && a[idx].y>=b[x].y) s.insert(a[idx++]);
                                                   ^