View Compilation Error

0_0_20966893_24474.cpp: In function 'void work(char)':
0_0_20966893_24474.cpp:18:27: error: 'swap' was not declared in this scope
     if (cmd=='1') swap(n,m);
                           ^
0_0_20966893_24474.cpp: In function 'void stkPush(char)':
0_0_20966893_24474.cpp:27:29: error: 'strchr' was not declared in this scope
         if (strchr(cd[i],cmd)!=NULL){
                             ^
0_0_20966893_24474.cpp:27:32: error: 'NULL' was not declared in this scope
         if (strchr(cd[i],cmd)!=NULL){
                                ^
0_0_20966893_24474.cpp:28:33: error: 'strlen' was not declared in this scope
             int len=strlen(sp[i]);
                                 ^
0_0_20966893_24474.cpp: In function 'int main()':
0_0_20966893_24474.cpp:39:31: error: 'scanf' was not declared in this scope
     while (~scanf("%d%d",&n,&m)){
                               ^
0_0_20966893_24474.cpp:43:25: error: 'strlen' was not declared in this scope
         int len=strlen(s);
                         ^
0_0_20966893_24474.cpp:46:29: error: 'printf' was not declared in this scope
         printf("%d %d\n",n,m);
                             ^