Help me in solving SDSQUARE problem

help
,
1

My issue

please help me identify error in my code

My code

#include<iostream>
#include<vector>
#include<string>
using namespace std;
bool isDigit(int n) {
    string s = to_string(n);
    for(int i=0;i<s.size();i++) {
        if(s[i]=='0' or s[i]=='1' or s[i]=='4' or s[i]=='9') continue;
        return false;
    }
    return true;
}
int main(){
    vector<int> v;
    for (int j = 1; j < 1E5+9; j++)
    {
        if (isDigit(j*j))
        {
            v.push_back(j*j);
        }
    }
    int T;
    cin>>T;
    for (int i = 0; i < T; i++)
    {
        int n,m;
        cin>>n>>m;
        cout<<lower_bound(v.begin(),v.end(),m+1)-lower_bound(v.begin(),v.end(),n)<<endl;
        
    }
    
    return 0;
}

Problem Link: SDSQUARE Problem - CodeChef