MLE，求调

#include<bits/stdc++.h>
using namespace std;
int main(){
    map<int,deque<int>> a;
    int q;
    cin>>q;
    while(q--){
        string s;
        cin>>s;
        if(s=="push_back"){
            int x,y;
            cin>>x>>y;
            a[x].push_back(y);
        }else if(s=="pop_back"){
            int x;
            cin>>x;
            if(!a[x].empty())a[x].pop_back();
        }else if(s=="push_front"){
            int x,y;
            cin>>x>>y;
            a[x].push_front(y);
        }else if(s=="pop_front"){
            int x;
            cin>>x;
            if(!a[x].empty())a[x].pop_front();
        }else if(s=="size"){
            int x;
            cin>>x;
            cout<<a[x].size()<<endl;
        }else if(s=="front"){
            int x;
            cin>>x;
            if(!a[x].empty())cout<<a[x].front()<<endl;
        }else{
            int x;
            cin>>x;
            if(!a[x].empty())cout<<a[x].back()<<endl;
        }
    }
    return 0;
}