#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC optimize("conserve-stack")
#include<bits/stdc++.h>
#define int long long
#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".ans","w",stdout)
#define pb push_back
#define mask(k) (1<<k)
#define checktime cerr << (double)clock() / CLOCKS_PER_SEC * 1000 << " ms";
using namespace std;
void phongbeo();
const int inf = 1e9;
const int mod2 = 1e9 + 7;
const int mod1 = 998244353;
const ll base=67;
int add(int x,int y)
{
if(x+y>=mod2) x-=mod2;
if(x+y<0) x+=mod2;
return x+y;
}
struct icd
{
long double a;
int b;
};
struct ib
{
int a;
int b;
};
struct ic
{
int a, b, c;
};
struct id
{
int a, b, c, d;
};
struct ie
{
int a, b, c, d, e;
};
int n, m, s1, s2, s4, s3, sf, k, s5, s6, mx, s7, s8, s9, mx2, res, dem2 = 0, dem = 0, s33, dem3, dem4, mid, l2, r2, center;
int i, s10, s12,k1,k2,k3,s11,t,lim,w,l,r;
int kk;
int el = 19;
main()
{
if(fopen(task".inp","r"))
{
fin(task);
// fou(task);
}
NHP
/// cin>>s1;
// modwwe
phongbeo(),down
// checktime
}
int a[200001];
int d[200001];
int c[200001];
void phongbeo()
{
cin>>n>>k>>k;
for(int i=1; i<=n; i++)
cin>>a[i];
for(int i=1; i<=k; i++)
cin>>l>>r,d[l]=r;
dem=0;
for(int i=1; i<=n; i++)
{
c[a[i]]++;
if(c[a[i]]==d[a[i]])dem++;
if(dem==k)
{
s2 =i;
break;
}
}
s3=1;
s4=inf;
if(dem!=k)
{
cout<<"impossible";
return;
}
l=1;
s4=inf;
c[a[s2]]--;
for(int i=s2; i<=n; i++)
{
c[a[i]]++;
while(true)
{
if(c[a[l]]==d[a[l]]) break;
c[a[l]]--;
l++;
}
s4=min(s4,i-l+1);
}
cout<<s4;
}
