int main(int argc, char **argv){
    char s[6];
    int n,i,t;
    unsigned int a[100001];
    unsigned short b[100001];
    unsigned int f[1001];
    unsigned int d;
    scanf("%d",&n);
     for(i=0;i<n;i++){
        scanf("%s", s);
        if(s[1]=='U'){
            scanf("%d %u", &t, &d);
            a[i]=d<<1;
            b[i]=f[t]>>1;
            a[i]+=f[t]&1;
            f[t]=i;
        }else{
            scanf("%d",&t);
            printf("%u\n",a[f[t]]>>1);
            f[t] = (((int)b[f[t]])<<1)+(a[f[t]]&1);
      }
    }
    return 0;
}

You should set f[0] - f[1001] = 0