求教啊，为什么过不了啊

#include<bits/stdc++.h>
using namespace std;
const int N=1e9+7;
#define ll long long
ll n,s,p,pos;
string str;

void solve(){
    cin>>n;
    cin>>str;
    pos=-1;
    p=0;
    s=0;
    for(ll i=0;i<n;i++){
        if(str[i]=='1'){
            if(pos==-1){
                pos=i;
                p++;
            }
            else{
                s=(s%N+(i%N-pos%N)*p%N)%N;
                p++;
                pos=i;
            }
        }
    }
    cout<<s%N;
}
int main(){
    int _=1;
    while(_--) solve();
}