func_code_string: #include <bits/stdc++.h>   void rd(int &x) {     x = 0;     int f = 1;     char ch = getchar();     while (ch <  0  || ch >  9 ) {       if (ch ==  - ) f = -1;       ch = getchar();     }     while (ch <=  9  && ch >=  0 ) x = x * 10 + ch -  0 , ch = getchar();     x *= f;   }   void lrd(long long &x) {     x = 0;     int f = 1;     char ch = getchar();     while (ch <  0  || ch >  9 ) {       if (ch ==  - ) f = -1;       ch = getchar();     }     while (ch <=  9  && ch >=  0 ) x = x * 10 + ch -  0 , ch = getchar();     x *= f;   }   const int INF = 1e9;   const long long LINF = 1e18;   const int mod = 998244353;   const int N = 3e5 + 10;   using namespace std;   int n;   int fi[N], nxt[N << 1], to[N << 1], tot;   void link(int x, int y) {     nxt[++tot] = fi[x];     fi[x] = tot;     to[tot] = y;   }   int f[N][3];   void dfs(int x) {     f[x][0] = f[x][1] = f[x][2] = 1;     int cnt = 1;     int ghb = 1;     for (int i = fi[x]; i; i = nxt[i]) {       if (f[to[i]][0]) continue;       dfs(to[i]);       cnt = cnt * 2 % mod;       int tmp;       tmp = (1ll * f[to[i]][0] * 2 + f[to[i]][1] + f[to[i]][2]) % mod;       f[x][0] = 1ll * f[x][0] * tmp % mod;       f[x][1] = 1ll * f[x][1] * (1ll * 2 * f[to[i]][0] + f[to[i]][1]) % mod;       ghb = 1ll * ghb * (f[to[i]][0] + f[to[i]][1]) % mod;       f[x][2] = 1ll * f[x][2] * (1ll * f[to[i]][0] * 2 + f[to[i]][1]) % mod;     }     f[x][1] = (f[x][1] - ghb + mod) % mod;   }   int main() {     rd(n);     for (int i = 1; i < n; i++) {       int x, y;       rd(x);       rd(y);       link(x, y);       link(y, x);     }     dfs(1);     printf( %d n , (f[1][0] + f[1][1] - 1) % mod);     return 0;   }   