#include <fstream>#include <stdio.h>#include <iostream>#include <string.h>#include <string>#include <limits.h>#include <algorithm>#include <math.h>#include <numeric>#include <functional>#include <ctype.h>#define MAX 100010#define INF 1000000000.00#define EPS 10e-6using namespace std;double dp[2][MAX],value[MAX];int num[MAX],list[MAX];int mark[MAX];int n,ncase=1,m;void setINF(const int &x){for(int i=0;i<=n;++i)dp[x][i]=INF;}int func(){setINF(0);for(int i=1;i<=n;++i)if(num[i]==list[1])dp[0][i]=min(dp[0][i-1],value[i]);elsedp[0][i]=dp[0][i-1];int cur=1,pre=0;for(int i=2;i<=m;++i){setINF(cur);for(int j=1;j<=n;++j)if(list[i]==num[j])dp[cur][j]=min(dp[cur][j-1],dp[pre][j-1]+value[j]);elsedp[cur][j]=dp[cur][j-1];pre=cur;cur=1-pre;}return pre;}int main(void){ while(~scanf("%d%d",&m,&n) && (m||n)) {memset(mark,0,sizeof(mark));for(int i=1;i<=m;++i)scanf("%d",&list[i]);int ind=0;for(int i=1;i<=n;++i)scanf("%d %lf",&num[i],&value[i]);int cur=func();if(dp[cur][n]+EPS<INF)printf("%.2lfn",dp[cur][n]);elseprintf("Impossiblen"); } return 0;}
