#include<cstdio>
#define max(a,b) ((a)>(b)?(a):(b))
const int MAXN = 1000000;
int siz[MAXN + 5], le[MAXN + 5], ri[MAXN + 5], v[MAXN + 5], ans;
bool check(int r1, int r2) {
if( v[r1] != v[r2] ) return false;
else if( r1 == 0 && r2 == 0 ) return true;
else return check(le[r1], ri[r2]) && check(ri[r1], le[r2]);
}
int dfs1(int rt) {
if( !rt ) return 0;
else return siz[rt] = dfs1(le[rt]) + dfs1(ri[rt]) + 1;
}
void dfs2(int rt) {
if( !rt ) return ;
if( siz[le[rt]] == siz[ri[rt]] )
if( check(le[rt], ri[rt]) ) ans = max(ans, siz[rt]);
dfs2(le[rt]), dfs2(ri[rt]);
}
int main() {
int n; v[0] = -1;
scanf("%d", &n);
for(int i=1;i<=n;i++)
scanf("%d", &v[i]);
for(int i=1;i<=n;i++) {
scanf("%d%d", &le[i], &ri[i]);
if( le[i] == -1 ) le[i] = 0;
if( ri[i] == -1 ) ri[i] = 0;
}
dfs1(1), dfs2(1);
printf("%d
", ans);
}