ll C[2d5][4],t;void f(ll i){rep(j,4){ll&s=C[j][i];if(t=C[i][j]&&s)s=0,wtN("("),f(t-1),wtN("methyl)");}}{ll@N;rep(i,N)rep(j,4){string@c;C[i][j]=c<"H"?stoi(c):0;}f(0);wt("methane");}