int towers=0, f=0;
     for(int i=0; i<N-1; i++) {
        if(lns[i]!=lns[i+1]) {
            f=0;
            towers++;
        }
        if(lns[i]==lns[i+1] && f==0) {
            f=1;
            towers++;
        }
    }
    if(N%2!=0)
        towers++;

    printf("%d",towers);