#define M(a,b)(a<b?b:a)
p,q,r=14,d,n,m;main(t){for(scanf("%d",&d);n=getchar(),~t;t=n-10?n:t)n-10?n-'o'?t<n|n<0?m=r>d?M(m,M(p,q)+d):M(m,p+q+r),p=q,q=0,r=1:r++:q++:0;n=!printf("%d",M(m,p+d));}