#include<iostream>#include<stdio.h>using namespace std;int f[304][304];int data[304];bool judge[304][304];int main( ) {int n,m;while(scanf("%d %d",&n,&m)!=EOF){for(int i=0;i<n;i++)for(int j=0;j<n;j++){judge[i][j]=false;f[i][j]=0;}for(int i=0;i<m;i++){int x,y;scanf("%d %d",&x,&y);judge[x][y]=judge[y][x]=true;}for(int i=0;i<n;i++){f[i][i]=0;scanf("%d",&data[i]);}for(int i=0;i<n-1;i++){if(judge[data[i]][data[i+1]])f[i][i+1]=2;}for(int r=2;r<n;r++){for(int i=0;i+r<n;i++){int j=i+r;bool tmpjudge = judge[data[i]][data[j]];for(int k=i;k<j;k++){int tmp=f[i][k]+f[k+1][j];if(f[i+1][k]+f[k+1][j-1]==j-i-1&&tmpjudge)tmp=tmp+2;if(tmp>f[i][j])f[i][j]=tmp;}}}printf("%dn",f[0][n-1]);}return 0;}
