#include <cstdio>
#include <cctype>
#include <algorithm>
#define repu(i,x,y) for (int i=x; i<=y; ++i)
#define repe(i,x) for (edge *i=fst[x]; i; i=i->nxt)
using namespace std;

typedef long long LL;
int n,s[200100],mind[200100],max1[200100],max2[200100];
LL ans;
char a[200100];
struct edge
{
    int v;
    edge *nxt;
} pool[400100],*tp=pool,*fst[200100];

int getint()
{
    char ch;
    while (!isdigit(ch=getchar()));
    int x=ch-'0';
    for (; isdigit(ch=getchar()); x=x*10+ch-'0');
    return x;
}

void update(int &x,int &y,int z)
{
    if (z>x)
        y=x,x=z;
    else
        y=max(y,z);
}

void dfs1(int x,int fa)
{
    s[x]=a[x]-'0',mind[x]=n;
    repe(i,x)
        if (i->v!=fa)
        {
            dfs1(i->v,x),s[x]+=s[i->v];
            update(max1[x],max2[x],max1[i->v]+1);
            if (s[i->v])
                mind[x]=min(mind[x],max1[i->v]+1);
        }
}

void dfs2(int x,int fa,int d)
{
    update(max1[x],max2[x],d);
    if (s[1]-s[x])
        mind[x]=min(mind[x],d);
    if (a[x]=='1')
        mind[x]=0;
    repe(i,x)
        if (i->v!=fa)
            dfs2(i->v,x,max1[i->v]+1==max1[x]?max2[x]+1:max1[x]+1);
}

int main()
{
    n=getint();
    repu(i,1,n-1)
    {
        int u=getint(),v=getint();
        *tp=(edge){v,fst[u]},fst[u]=tp++;
        *tp=(edge){u,fst[v]},fst[v]=tp++;
    }
    scanf("%s",a+1);
    dfs1(1,0),dfs2(1,0,0);
    repu(i,1,n)
        ans+=max(0,min(max1[i]-1,max2[i]+1)-mind[i]+1);
    printf("%lld\n",ans+1);
    return 0;
}