cf Sereja and Array

http://codeforces.com/contest/315/problem/B

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 #include <algorithm>
 #define maxn 200000
 using namespace std;

 int a[maxn],b[maxn],c,v,x;

 int main()
 {
     int n,m;
     cin>>n>>m;
     for(int i=; i<n; i++)
     {
         cin>>a[i];
     }
     int ans=;
     for(int i=; i<m; i++)
     {
         cin>>c;
         if(c==)
         {
             cin>>v>>x;
             a[v-]=x-ans;
         }
         else if(c==)
         {
             cin>>x;
             ans+=x;
         }
         else if(c==)
         {
             cin>>v;
             cout<<a[v-]+ans<<endl;
         }
     }
     return ;
 }