Language: C

n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}

Compiler output:
main.c:1:1: warning: data definition has no type or storage class
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      | ^
main.c:1:1: error: type defaults to 'int' in declaration of 'n' [-Wimplicit-int]
main.c:1:3: error: type defaults to 'int' in declaration of 'k' [-Wimplicit-int]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |   ^
main.c:1:5: error: type defaults to 'int' in declaration of 'i' [-Wimplicit-int]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |     ^
main.c:1:7: error: type defaults to 'int' in declaration of 'y' [-Wimplicit-int]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |       ^
main.c:1:11: warning: multi-character character constant [-Wmultichar]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |           ^~~~~
main.c:1:9: warning: data definition has no type or storage class
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |         ^
main.c:1:9: error: type defaults to 'int' in declaration of 'd' [-Wimplicit-int]
main.c:1:18: error: return type defaults to 'int' [-Wimplicit-int]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |                  ^
main.c:1:40: error: return type defaults to 'int' [-Wimplicit-int]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |                                        ^~~~
main.c: In function 'main':
main.c:1:40: error: type of 'x' defaults to 'int' [-Wimplicit-int]
main.c:1:52: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |                                                    ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
main.c:1:52: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |                                                    ^~~~~
main.c:1:52: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:1:91: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |                                                                                           ^~~~~~
main.c:1:91: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:91: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:1:91: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:1:105: error: 's' undeclared (first use in this function)
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |                                                                                                         ^
main.c:1:105: note: each undeclared identifier is reported only once for each function it appears in
main.c:1:151: error: implicit declaration of function 'qsort' [-Wimplicit-function-declaration]
    1 | n,k,i,y;d['   '];c(int*z){i=*1[&z]-*z;}main(x){for(scanf("%*d");~scanf("%d%d%d",&n,&k,&y);printf("%u\n",s)){for(i=--n;i;y=x)scanf("%d",&x),d[--i]=x-y;qsort(d,n,4,c);for(s=0;n>=k;s+=d[--n]);}}
      |                                                                                                                                                       ^~~~~