Language: Java

import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
    String N =sc.next();
    for(int A=0;A<25;A++){
      if(N==M[A]){System.out.println(M[A+1]);System.exit(0);}}
  }
}

Compiler output:
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                 ^
  symbol:   variable a
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                   ^
  symbol:   variable b
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                     ^
  symbol:   variable c
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                       ^
  symbol:   variable d
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                         ^
  symbol:   variable e
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                           ^
  symbol:   variable f
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                             ^
  symbol:   variable g
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                               ^
  symbol:   variable h
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                 ^
  symbol:   variable i
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                   ^
  symbol:   variable j
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                     ^
  symbol:   variable k
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                       ^
  symbol:   variable l
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                         ^
  symbol:   variable m
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                           ^
  symbol:   variable n
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                             ^
  symbol:   variable o
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                               ^
  symbol:   variable p
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                 ^
  symbol:   variable q
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                   ^
  symbol:   variable r
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                     ^
  symbol:   variable s
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                       ^
  symbol:   variable t
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                         ^
  symbol:   variable u
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                           ^
  symbol:   variable v
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                             ^
  symbol:   variable w
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                               ^
  symbol:   variable x
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                                 ^
  symbol:   variable y
  location: class Main
Main.java:5: error: cannot find symbol
    String M[] ={a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z};
                                                                   ^
  symbol:   variable z
  location: class Main
26 errors