foo.cpp: In function 'int main()':
foo.cpp:11:15: error: 'getchar' was not declared in this scope
     b=getchar();
               ^
foo.cpp:21:15: error: 'getchar' was not declared in this scope
     c=getchar();
               ^
foo.cpp:81:17: error: 'putchar' was not declared in this scope
     putchar(e[i]);
                 ^
foo.cpp:7:17: warning: unused variable 't' [-Wunused-variable]
     int n=0,m=0,t,i,j;
                 ^