const fs = require("fs");
const input = fs.readFileSync("/dev/stdin").toString().split("\n");
const craneCnt = Number(input[0]);
const craneArr = input[1].split(" ").map((n) => Number(n));
craneArr.sort((a, b) => b - a);
const boxCnt = Number(input[2]);
const boxArr = input[3].split(" ").map((n) => Number(n));
boxArr.sort((a, b) => b - a);
if (boxArr.at(0) > craneArr[0]) {
console.log(-1);
return;
}
let answer = 0
while(boxArr.length){
answer+=1
for(let i=0; i<craneCnt; ++i){
for(let j=0; j<boxArr.length; ++j){
if(craneArr[i]>=boxArr[j]){
boxArr.splice(j,1)
break;
}
}
}
}
console.log(answer)