#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <iostream>#include <queue>using namespace std;typedef long long ll;int const MAXN = 100000+1;ll dp[100+1][200+5];struct D{ int v,d;}sta[100+1];int gmin(int a,int b){return a<b?a:b;}int main(){ memset(dp,-1,sizeof(dp)); int v,d,tot=0; int n; scanf("%d",&n); while(scanf("%d%d",&d,&v)!=EOF){ sta[tot].v = v; sta[tot++].d = d; } sta[tot].d = n; sta[tot++].v = 0; int i,j; int st = 0,bottom=-1; if(sta[st].d>100){ printf("Impossiblen"); return 0; } for(st = 100-sta[0].d; st>=0; st--){ dp[0][st]=0; } for(i=0; i<tot-1; i++){ d = sta[i].d; v = sta[i].v; int nd = sta[i+1].d; int nv = sta[i+1].v;///鍒嗗埆涓哄綋鍓嶈妭鐐箆锛宒鍜屼笅涓粨鐐箆锛宒 bottom=-1; for(j=0; j<=200; j++){ if(dp[i][j]==-1) continue; if(bottom==-1) bottom=j; } int mmin = 0; if(bottom==-1) break; for(j=bottom+1; j<=200; j++){ if(dp[i][j]==-1) dp[i][j] = dp[i][j-1] + v ; else dp[i][j] = gmin(dp[i][j],dp[i][j-1] + v ); if(bottom>=nd-d) dp[i+1][j-bottom] = dp[i][j]; } if(nd-d>200) break; if(bottom < nd-d) for(j=(200-nd+d); j>=0; j--) dp[i+1][j] = dp[i][j+nd-d]; } if(dp[tot-1][100]==-1) printf("Impossiblen"); else printf("%I64dn",dp[tot-1][100]); return 0;}
