View Compilation Error

0_0_37959410_13033.cpp: In function 'void solve()':
0_0_37959410_13033.cpp:11:64: error: 'lcm' was not declared in this scope
     for(int i=1;i<=n;i++)cin>>s[i],mx=lcm(mx,(int)s[i].length());
                                                                ^