View Compilation Error

0_0_36018305_31633.cpp: In function 'void dfs(long long int, long long int)':
0_0_36018305_31633.cpp:52:45: error: 'x' cannot be used as a function
         while(l<r&&(y(r)-y(r-1))*dis[v]<(x(r)-x(r-1))*(f[v]+dis[v]*dis[v])){
                                             ^
0_0_36018305_31633.cpp:52:52: error: 'x' cannot be used as a function
         while(l<r&&(y(r)-y(r-1))*dis[v]<(x(r)-x(r-1))*(f[v]+dis[v]*dis[v])){
                                                    ^