CodeForces 652C Foe Pairs

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;

const int maxn=4*100000+10;

int n,m;
int a[maxn],b[maxn];
int p[maxn];

int dp[maxn];

int main()
{
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
    {
        scanf("%d",&a[i]);
        p[a[i]]=i;
    }

    for(int i=1;i<=n;i++) b[i]=0x7FFFFFFF;

    for(int i=1;i<=m;i++)
    {
        int li,ri;scanf("%d%d",&li,&ri);
        int fx=p[li];
        int fy=p[ri];
        if(fx>fy) swap(fx,fy);
        b[fx]=min(b[fx],fy);
    }

    dp[n]=b[n];
    for(int i=n-1;i>=1;i--)
    {
        if(b[i]==0x7FFFFFFF) dp[i]=min(dp[i+1],b[i]);
        else dp[i]=min(dp[i+1],b[i]-1);
    }

    long long ans=0;

    for(int i=1;i<=n;i++)
    {
        if(dp[i]==0x7FFFFFFF) ans=ans+(long long)(n-i+1);
        else ans=ans+(long long)(dp[i]-i+1);
    }
    printf("%lld\n",ans);

    return 0;
}