int n,d[9],z,x,o;
string y="yuki",s;
{rd(n,s);rep(i,s.size()){o=1;rep(j,0,8,2){if(s[i]>=y[j/2]){o=0;d[j+(s[i]==y[j/2])]++;break;}}if(o)d[8]++;}reverse(d,d+9);z = (d[1]>d[0]?d[0]+(d[1]-d[0])/2:d[1]);rep(i,2,7,2){x = min(d[i],d[i+1]);if(d[i+1]>d[i]){d[i+1]-=d[i];x+=min(d[i+1],z);if(d[i+1]>z)x+=(d[i+1]-z)/2;}z=x;}wt(z+d[8]);}