#include <bits/stdc++.h>
using namespace std;
#define INF 999999999999
#define Size 10005

struct Pilot{
    long long cap;
    long long ast;
};

Pilot A[Size];
long long DP[Size][5005];
int N;

long long call(int cur,int cnt){
    if(cnt - (N-cur) > 0) return INF;
    if(cur == N){
        if(cnt == 0) return 0;
        return INF;
    }
    if(DP[cur][cnt] != -1) return DP[cur][cnt];
    long long res = INF;
    if(cnt > 0){
        long long r1 = call(cur+1,cnt+1) + A[cur].ast;
        long long r2 = call(cur+1,cnt-1) + A[cur].cap;
        res = min(r1,r2);
    }else{
        res = call(cur+1,cnt+1) + A[cur].ast;
    }
    return DP[cur][cnt] = res;
}

int main() {
    scanf("%d",&N);
    for(int i = 0;i<N;i++){
        scanf("%lld %lld",&A[i].cap,&A[i].ast);
    }
    memset(DP,-1,sizeof(DP));
    long long res = call(0,0);
    printf("%lld\n",res);
    return 0;
}